GST Interest Calculator
Calculate interest payable on delayed GST payments under Indian GST law. Supports both 18% (normal delay) and 24% (wrong/excess ITC) interest rates with instant calculations.
Introduction
Missed a GST payment deadline? This calculator computes the interest you owe under Section 50 of the CGST Act. Enter your unpaid tax amount, pick the interest rate (18% for normal delays or 24% for wrong/excess ITC claims), and specify how many days late you are—or just select the due date and payment date. Results show the interest amount, total payable including tax, and a clear breakdown. Whether you're filing a late GSTR-3B, correcting ITC claims, or responding to a GST notice, this tool helps you calculate exact interest liability instantly. Everything calculates in your browser, so your tax figures and business information stay private on your device. The calculator follows official GST interest calculation methods prescribed by the Central Board of Indirect Taxes and Customs, ensuring accuracy for compliance purposes. Business owners, accountants, tax consultants, and anyone managing GST compliance can use this tool to estimate interest costs, plan payments, and avoid surprises during return filing or audits.
Who Should Use This Tool?
- Businesses filing late GSTR-3B returns
- Accountants calculating client interest liability
- Small traders missing GST payment due dates
- Tax consultants advising on GST delays
- Companies reversing wrong ITC claims
- Finance teams reconciling GST accounts
- Startups learning GST compliance
- CAs responding to GST notices
- E-commerce sellers managing tax payments
- Manufacturers correcting ITC mismatches
How This Tool Works
The GST Interest Calculator uses the interest calculation formula prescribed under Section 50 of the CGST Act. For normal tax payment delays, it applies 18% per annum interest: Interest = (Tax Amount × 18% × Number of Days) / 365. For wrong or excess input tax credit reversals, it uses 24% per annum: Interest = (Tax Amount × 24% × Number of Days) / 365. The calculator computes daily interest by dividing the annual rate proportionately, ensuring precise calculations even for short delays of just a few days. You can either enter the delay period in days directly, or select the due date and actual payment date—the tool automatically calculates the number of days between them. The result displays three key figures: the interest amount payable, the original tax liability, and the total amount you need to pay (tax plus interest). All calculations happen instantly in your browser using JavaScript, keeping your financial information private. The tool handles leap years and varying month lengths correctly when computing day counts from calendar dates, ensuring accuracy in all scenarios.
Try GST Interest Calculator Now
Use the interactive tool below to get instant results
GST Interest Calculator
Calculate interest payable on delayed GST payments under Section 50 of CGST Act. Enter tax amount, interest rate, and delay period to get instant calculations.
Enter the GST tax amount on which interest is to be calculated
For reference only. Does not affect interest calculation.
Disclaimer: This GST Interest Calculator is for informational purposes only. Interest calculations are indicative and may vary based on applicable GST provisions, notifications, and case-specific interpretations. Users should verify calculations with a tax professional before making payments. This tool does not constitute tax advice.
How to Use GST Interest Calculator
Enter GST Tax Amount
Input the unpaid GST tax amount on which you need to calculate interest. This is the principal amount on which interest will be computed according to GST law.
Select Interest Rate
Choose 18% per annum for normal delays in GST payment or 24% per annum for cases involving wrong or excess input tax credit (ITC) availed under Section 50 of CGST Act.
Enter Delay Period
Either enter the number of delayed days directly, or select the due date and actual payment date. The calculator will automatically compute the number of days and calculate interest accordingly.
Review Interest and Total Payable
Check the calculated interest amount, total payable (tax + interest), and the breakdown. Use the copy button to quickly copy the interest amount for payment or record-keeping purposes.
Use Cases for GST Interest Calculator
Businesses Filing Late GSTR-3B Returns
GSTR-3B is the monthly or quarterly summary return that most GST-registered businesses file. The due date is typically the 20th of the following month for monthly filers, or specific quarterly deadlines for QRMP (Quarterly Return Monthly Payment) scheme taxpayers. When you miss this deadline and file late, GST law requires you to pay interest on the unpaid tax liability from the due date until the actual payment date. Imagine you're a small manufacturing business. Your GSTR-3B for March 2026 was due on April 20, 2026. However, due to cash flow issues, you couldn't pay the tax immediately. You finally make the payment on May 10, 2026—a delay of 20 days. Your total tax liability for March was ₹75,000. According to Section 50(1) of the CGST Act, you must pay interest at 18% per annum on delayed payment. Using the GST Interest Calculator, you enter ₹75,000 as the tax amount, select 18% interest rate, and enter 20 days as the delay period. The calculator instantly shows that your interest liability is ₹739.73 (approximately). So your total payment becomes ₹75,739.73. This amount must be paid in addition to the tax to regularize your return filing and avoid further notices from the GST department. What many businesses don't realize is that interest starts accruing from the day after the due date. Even if you file your GSTR-3B return on time but delay the tax payment, interest is still applicable. The late fee (which is separate from interest) applies if you file the return late, but interest applies specifically on delayed tax payment regardless of when you file the return. For businesses with recurring cash flow issues, these interest charges can accumulate quickly. If you delay payments by 30, 45, or 60 days, the interest amounts become substantial. A ₹1 lakh tax liability delayed by 60 days at 18% attracts approximately ₹2,959 in interest. Over a year, with multiple returns, this adds up significantly and impacts profitability. The GST Interest Calculator helps you estimate these costs upfront, allowing you to plan your cash flow better. If you know you're going to delay a payment by 15-30 days, you can calculate the interest liability and factor it into your financial planning. This transparency helps businesses make informed decisions about when to prioritize GST payments versus other operational expenses. One important note: interest is calculated on the net tax liability, not the gross tax. If you have input tax credit (ITC) available, you can utilize it to reduce your tax liability before calculating interest. For example, if your output tax is ₹1 lakh but you have ₹40,000 in ITC, your net liability is ₹60,000. Interest is calculated only on this ₹60,000, not the full ₹1 lakh. However, if you claimed ITC that you weren't entitled to (wrong or excess ITC), and you're now reversing it, the interest rate increases to 24% per annum. This higher rate applies specifically to situations where incorrect ITC claims are being corrected. The calculator allows you to select between 18% and 24% rates to handle both scenarios accurately.
Small Traders Missing GST Payment Due Dates
Small traders—retail shops, kirana stores, garment retailers, electronics dealers—often operate with tight cash flows and limited accounting support. Missing a GST payment due date is common, especially during festival seasons when inventory purchases are high or when receivables from customers are delayed. When this happens, interest becomes payable, and knowing how much you owe helps avoid surprises when filing returns or receiving notices from the GST department. Let's say you run a small garment store. Your GSTR-3B for January 2026 was due on February 20, 2026, with a tax liability of ₹15,000. You were expecting a bulk payment from a B2B customer that got delayed, so you couldn't pay the tax on time. You eventually make the payment on March 5, 2026—a delay of 13 days. You need to know how much interest you'll have to pay along with the tax. Using the calculator, you input ₹15,000 as the tax amount, select 18% interest rate, and enter 13 days. The result shows interest of approximately ₹95.34. So your total payment is ₹15,095.34. While ₹95 might not seem significant individually, if this happens multiple times across several months, the cumulative interest adds up and becomes a noticeable expense. For small traders, understanding interest liability also helps in deciding whether to borrow money to pay GST on time. If you can access a short-term loan at 12-15% annual interest, it might be more economical than paying 18% GST interest. The calculator helps you make this cost comparison quickly. Another scenario: seasonal businesses like those selling festive items, winter clothing, or agricultural products might face periods of zero or minimal revenue. During off-seasons, paying GST from the previous busy season becomes challenging. If you delay payment by 45 days, the interest adds up. For a ₹50,000 tax liability delayed by 45 days at 18%, you're looking at around ₹1,109 in interest. Knowing this in advance helps you negotiate better with suppliers or plan your finances differently. Small traders also sometimes confuse GST interest with late fees. Late fees are fixed amounts (₹50 per day for CGST and ₹50 per day for SGST, capped at certain limits) charged for filing returns late. Interest, on the other hand, is calculated as a percentage of unpaid tax and has no cap. If your tax liability is high and the delay is long, interest can be much more than late fees. The calculator focuses specifically on interest, helping you understand this component separately. It's also worth noting that interest calculations don't distinguish between deliberate and unavoidable delays. Whether you missed the payment due to cash shortage, bank holidays, technical issues on the GST portal, or simply oversight, the interest rate remains the same. The GST law doesn't have provisions for waiver based on reasons for delay, making it critical to plan payments carefully or at least understand the cost implications when delays are unavoidable.
Wrong ITC Claims and Reversals at 24% Interest
Input Tax Credit (ITC) is one of the most valuable features of GST—it allows businesses to claim credit for tax paid on purchases and reduce their output tax liability. However, ITC claims are subject to strict conditions. If you claim ITC that you weren't entitled to (wrong ITC) or claim more than what was actually available (excess ITC), and the department or your auditor identifies this error, you must reverse the incorrect ITC and pay interest at 24% per annum from the date you wrongly claimed it until the date you reverse it. Let's understand with an example. Suppose you're a manufacturer who purchased raw materials worth ₹5 lakhs + 18% GST (₹90,000 tax) in January 2026. You claimed the full ₹90,000 as ITC in your January GSTR-3B. However, in March 2026, during internal reconciliation, you realize that invoices worth ₹2 lakhs of those purchases were actually for goods used for personal purposes, not for business. As per GST law, ITC is not available on goods or services used for personal consumption. This means ₹36,000 (18% of ₹2 lakhs) was wrongly claimed ITC. You need to reverse this amount. You claimed it in January (let's say you filed on February 20), and you're reversing it in March (filed on April 20). The period between February 20 and April 20 is 60 days. Section 50(3) of the CGST Act specifies that when you reverse wrong or excess ITC, you must pay interest at 24% per annum on the amount from the date of wrong availment until reversal. Using the calculator, you enter ₹36,000, select 24% interest rate, and enter 60 days. The calculator shows interest of approximately ₹1,421. So when you reverse the ITC, you not only reduce your available credit by ₹36,000 but also pay ₹1,421 as interest. This makes wrong ITC claims expensive and emphasizes the importance of accurate ITC reconciliation. Another common scenario involves claiming ITC on invoices that haven't been uploaded by suppliers in GSTR-1. GST rules allow you to provisionally claim ITC, but if the supplier doesn't upload the invoice within a specified period, you must reverse the ITC. If you delay reversing it beyond the deadline, the 24% interest starts applying. For instance, if you claimed ₹50,000 ITC in April but the supplier never uploaded those invoices, and you should have reversed it by September but actually reversed in December (a 90-day delay), the interest on ₹50,000 at 24% for 90 days is approximately ₹2,959. Excess ITC claims can also happen due to calculation errors. Suppose you mistakenly entered ₹1,80,000 as ITC instead of ₹80,000 in a return due to a typo. The excess ₹1,00,000 claimed attracts 24% interest from the date of wrong availment until you correct it. If you catch this error after 30 days, the interest on ₹1 lakh at 24% for 30 days is around ₹1,973. The distinction between 18% and 24% interest is crucial. Normal delays in paying tax attract 18%, but errors involving ITC attract 24%. This higher rate is intended to discourage incorrect ITC claims, which directly impact government revenue. When using the calculator, selecting the correct interest rate is essential for accurate liability estimation. It's also important to understand that interest on ITC reversals is calculated from the date of wrong availment, not from the due date of the subsequent return. This makes the interest period potentially longer and more expensive. If you claimed wrong ITC in January and reverse it in April, the interest period could be 90+ days, depending on exact dates.
Accountants Estimating Interest Liability for Clients
Chartered accountants, tax consultants, and bookkeepers managing GST compliance for multiple clients frequently encounter situations where interest calculations are needed. Whether it's advising clients on the cost of delaying payments, reconciling past returns, or preparing for GST audits, understanding interest liability is part of the CA's toolkit. The GST Interest Calculator streamlines this process, allowing quick estimations without manual calculations. Consider a CA managing accounts for 20 small business clients. During monthly GST filing, three clients inform that they can't pay their tax liability on time due to cash flow issues. One has a ₹30,000 liability and expects a 10-day delay. Another has ₹85,000 and might delay by 25 days. The third has ₹1,50,000 and can pay only after 40 days. The CA needs to quickly estimate interest costs for each client to help them make informed decisions. Using the calculator, the CA computes: Client 1: ₹30,000 × 18% × 10 days = ₹148 interest. Client 2: ₹85,000 × 18% × 25 days = ₹1,046 interest. Client 3: ₹1,50,000 × 18% × 40 days = ₹2,959 interest. With these numbers, the CA can advise Client 3 that considering a short-term loan to pay GST on time might be more cost-effective than paying ₹2,959 in interest, while Clients 1 and 2 might find the interest cost acceptable compared to arranging immediate funds. Another scenario: during annual GST audit (GSTR-9 and 9C), CAs often discover discrepancies between books and GST returns filed during the year. These might include forgotten tax liabilities, unclaimed ITC, or classification errors. When correcting these in the annual return or through amendments, interest becomes payable. If a client missed reporting ₹2 lakhs of tax liability in March 2025, and it's now being corrected in March 2026 (a year later), the interest at 18% for 365 days on ₹2 lakhs is ₹36,000—a significant amount that impacts the client's financials. CAs also use interest calculations when responding to GST notices. If the department issues a show-cause notice pointing out undeclared tax liability of ₹1 lakh from a transaction six months ago, the CA needs to calculate the interest liability up to the date of expected payment to advise the client on total outflow. The calculator makes this instant and accurate. For clients under GST scrutiny or investigation, interest calculations become critical in settlement discussions. If the department demands ₹5 lakhs in unpaid tax from two years ago, the interest at 18% for 730 days is approximately ₹1,80,000. Including penalties, the total demand could be ₹7-8 lakhs or more. Knowing the interest component helps the CA negotiate or prepare the client for the payment. CAs also deal with ITC mismatches—situations where the client's claimed ITC doesn't match the supplier's reported outward supply. Resolving these often involves ITC reversals and corresponding interest at 24%. If mismatches of ₹3 lakhs are identified spanning 4-6 months, the interest alone could be ₹15,000-20,000. The calculator helps quantify this liability quickly during reconciliation meetings. One practical tip for CAs: maintain a record of interest calculations for each client, especially when advising on delayed payments or corrections. This documentation serves as evidence of due diligence during audits or disputes and helps clients understand the costs involved in GST compliance decisions.
New GST Registrants Understanding Interest Obligations
New businesses registering under GST often lack clarity on interest obligations. They understand that tax must be paid, but the concept of interest on delayed payment, calculation methods, and rates can be confusing. For startups, small enterprises, and first-time GST registrants, a clear understanding of interest helps avoid penalties and financial surprises in the early months of business. Imagine you're a freelance graphic designer who just crossed the ₹20 lakh turnover threshold and registered for GST. You file your first GSTR-3B for February 2026, which is due on March 20, 2026. Your tax liability is ₹12,000. Being new to GST processes, you're unsure about payment procedures and end up paying on March 28—8 days late. You wonder: "Do I owe any additional amount?" Yes, you do. GST law mandates interest at 18% per annum on delayed tax payments. Using the calculator, ₹12,000 at 18% for 8 days results in approximately ₹47 interest. While small, this is still payable, and failing to pay it can cause issues during future filings or audits. New registrants often miss such details, and the calculator serves as an educational tool to understand these obligations. Another common scenario for new registrants: misunderstanding due dates. If you're a quarterly filer under the QRMP scheme, your GSTR-3B for the quarter ending March is due in April. But the exact date (like April 22 or 24) depends on your state and scheme. New registrants sometimes assume the due date is the end of the month, pay late, and incur interest. Using the calculator with the correct due date and actual payment date shows the exact interest liability. New businesses also often face the wrong ITC scenario unknowingly. For instance, you might claim ITC on expenses like mobile phone bills, office snacks, or health insurance, not realizing that ITC is blocked on certain goods and services under GST law. When you later discover (or an auditor points out) that ₹15,000 of claimed ITC was ineligible, you must reverse it with 24% interest. For a 60-day period, this is approximately ₹591. Understanding that correcting mistakes comes with an interest cost encourages careful ITC claims from the start. First-time GST filers might also not know that interest applies even if the delay was due to technical issues on the GST portal, bank processing delays, or public holidays. The law doesn't provide exemptions for such reasons. If the due date is the 20th and you pay on the 21st because the portal was down on the 20th, technically interest is applicable for one day. While one day's interest is minimal, the principle is important to understand. New registrants should also know that interest is self-assessed. The GST portal doesn't automatically calculate or demand interest when you make a delayed payment. You must calculate it yourself and pay it through the Electronic Cash Ledger under the appropriate interest head (CGST interest, SGST interest, IGST interest). Many new businesses skip this step, assuming that if the portal accepted their tax payment, everything is settled. However, during reconciliation or audits, the department can demand unpaid interest with additional interest on the interest amount. The GST Interest Calculator is particularly useful for new registrants as a learning tool. By experimenting with different scenarios—"What if I delay by 10 days? 30 days? What if I have a ₹50,000 liability vs. ₹10,000?"—you develop an intuition for how interest works and the financial impact of delays. This knowledge helps you prioritize GST payments in your cash flow planning.
Compliance Reviews and Internal Audits
Businesses conducting internal compliance reviews or preparing for external GST audits often need to verify whether past GST payments were made on time and whether any interest liabilities were overlooked. The GST Interest Calculator becomes a verification tool during such reviews, helping accountants and auditors identify and quantify interest obligations that might have been missed in routine filings. Consider a mid-sized company conducting an annual GST compliance review in March 2026, looking back at all filings from the previous financial year (April 2025 to March 2026). The finance team pulls up records for all 12 GSTR-3B returns and checks payment dates against due dates. They discover: - In May 2025, tax of ₹2,00,000 was paid 5 days late - In August 2025, ₹1,50,000 was paid 12 days late - In December 2025, ₹3,00,000 was paid 18 days late For each instance, the team uses the calculator to determine interest liability. May: ₹2,00,000 × 18% × 5 days = ₹493. August: ₹1,50,000 × 18% × 12 days = ₹887. December: ₹3,00,000 × 18% × 18 days = ₹2,663. Total overlooked interest for the year: ₹4,043. While not massive, this needs to be paid to regularize records before the annual return (GSTR-9) is filed and before external auditors review the books. Internal audits also look at ITC claims and reversals. If the audit reveals that in June 2025, the company claimed ₹50,000 ITC on an invoice that was later cancelled by the supplier in September 2025, but the reversal wasn't processed until November 2025, there's a delay of 60 days (September to November) in reversing wrong ITC. At 24% interest on ₹50,000 for 60 days, the company owes approximately ₹1,973 in interest. The calculator helps quantify such exposures during compliance reviews. External auditors (CAs conducting statutory audits or GST audits) use interest calculations to assess a company's GST compliance quality. If they find multiple instances of delayed payments with unpaid interest, it signals weak compliance processes and cash flow management issues. Conversely, if payments are timely or delays are accompanied by correctly calculated and paid interest, it indicates strong compliance discipline. During pre-audit preparations, companies use the calculator to proactively identify and settle any pending interest liabilities. This reduces the risk of adverse audit findings and potential demands from the GST department. For instance, if a company discovers during self-review that ₹5,00,000 in tax was paid 30 days late six months ago, and the interest of ₹7,397 wasn't paid, they can settle it before the auditor or department notices. Compliance reviews also involve scenario planning. For example, if the company is considering delaying next month's GST payment by 15 days to manage cash flow during a slow period, the CFO uses the calculator to estimate the cost. If the liability is ₹4,00,000, the interest for 15 days at 18% is approximately ₹2,959. The CFO can then decide whether this cost is acceptable or whether alternative financing should be arranged. Quarterly or annual compliance reviews often reveal patterns. If a company consistently pays GST 5-10 days late month after month, the cumulative interest over a year becomes significant. For instance, ₹2,00,000 average monthly liability paid 7 days late every month for 12 months results in ₹2,466 annual interest (₹2,00,000 × 18% × 7 days × 12 months / 365). Identifying such patterns through systematic review and calculation helps improve payment discipline.
Cash Flow Planning for Delayed GST Payments
Many businesses face temporary cash flow constraints—seasonal revenue cycles, delayed customer payments, inventory buildup, or unexpected expenses. During such periods, delaying GST payments might be a conscious financial decision. The GST Interest Calculator helps businesses quantify the cost of this decision and plan cash flow accordingly, treating interest as a known expense rather than a surprise liability. Imagine a garment wholesale business that operates on 60-90 day credit terms with retail customers. In January 2026, the business ships goods worth ₹50 lakhs to retailers, expecting payment in March-April. However, GST on these sales (say ₹6 lakhs) is payable in February 2026 (for January sales). The business faces a liquidity gap—the goods are sold, GST is collected from customers (embedded in the sale price), but actual cash payment from customers is pending. The business has two options: 1) Arrange a short-term working capital loan to pay GST on time, or 2) Delay GST payment until customer payments arrive, and pay interest. To make this decision, the CFO uses the calculator. If the expected delay is 30 days on a ₹6 lakh liability, the interest at 18% is approximately ₹8,876. If the working capital loan costs 15% per annum for 30 days, that's ₹7,397. The loan is marginally cheaper, but the difference is small. Considering loan processing time and effort, the business might choose to delay GST and pay the ₹8,876 interest. Another scenario: a startup in its first year of operations has uneven revenue. Some months are profitable; others barely break even. In a lean month, the GST liability is ₹30,000. The startup has ₹25,000 available, leaving a ₹5,000 shortfall. The founder uses the calculator to estimate interest if this ₹5,000 is paid 15 days late: ₹5,000 × 18% × 15 days = ₹37. This is a negligible amount, so the founder decides to delay that portion, pay ₹25,000 immediately, and settle the ₹5,037 two weeks later when client payments arrive. This strategic use of the interest calculation prevents business disruption while staying legally compliant. For businesses with multiple GST liabilities across states (if registered in multiple states due to inter-state operations), cash flow planning becomes complex. Suppose a company has ₹2 lakhs liability in State A and ₹1 lakh in State B, both due on the 20th. If cash is tight, the business might decide to pay State A on time and delay State B by 10 days, incurring ₹493 interest on the ₹1 lakh. The calculator helps make this prioritization decision transparently. Seasonal businesses—like those in tourism, agriculture, or festive products—have pronounced cash flow cycles. During peak season, revenue is high, and GST payments are easy. During off-season, revenue drops, but if there were sales in the previous month, GST is still payable. Planning for this involves estimating interest costs if payments are delayed during lean months. For instance, if a tourism business has ₹1,50,000 GST liability from March (peak season) payable in April (off-season), and expects a 20-day delay, the interest is ₹1,479. Knowing this in advance helps the business reserve funds or adjust pricing strategies. Cash flow planning also applies to large one-time transactions. If a business sells a major asset or a bulk order with ₹10 lakh GST liability, and the customer's payment is delayed by 45 days, the business can calculate that delaying GST payment by 45 days on ₹10 lakhs costs ₹22,192 in interest. This cost can be factored into negotiations with the customer or into pricing for future similar transactions. Finally, businesses using the calculator for cash flow planning should remember that interest is just one component of delayed payment costs. Late fees (if the return is also filed late), potential notices from the department, and the administrative burden of managing delays also factor into the total cost. The calculator provides the financial cost, which is the most quantifiable part of the decision.
Key Features
Dual Interest Rates
Supports both 18% (normal delay) and 24% (wrong/excess ITC) interest rates as per CGST Act Section 50.
Flexible Date Input
Enter delay days directly or select due date and payment date for automatic day count calculation.
Instant Calculations
Results appear immediately with interest amount, total payable, and detailed breakdown clearly displayed.
Copy Functionality
Quick copy button for interest amounts makes payment processing and record-keeping efficient.
Complete Privacy
All calculations happen in your browser. Tax amounts and business data never leave your device.
Section 50 Compliant
Follows official GST interest calculation methods prescribed by CBIC for accurate compliance.
Frequently Asked Questions
What is the difference between 18% and 24% interest rates?
The 18% per annum rate applies to normal delays in paying GST tax liability (Section 50(1) of CGST Act). The 24% per annum rate applies specifically when reversing wrong or excess input tax credit claims (Section 50(3)). Choose the rate based on your specific situation.
When does interest start accruing on GST payments?
Interest starts accruing from the day after the due date for GST payment, regardless of when you file the return. Even if you file GSTR-3B on time but delay the tax payment, interest applies from the original due date until actual payment.
Is interest calculated on gross tax or net tax liability?
Interest is calculated on net tax liability after utilizing available input tax credit (ITC). If your output tax is ₹1 lakh but you have ₹40,000 ITC, interest applies only to the net ₹60,000 liability, not the full amount.
Can GST interest be waived based on valid reasons for delay?
No, GST law does not provide provisions for interest waiver based on reasons for delay. Whether the delay was due to cash shortage, bank holidays, technical issues, or oversight, the interest rate and calculation remain the same.
Are my tax amounts and calculations stored anywhere?
No. All calculations happen in your browser using JavaScript. The tax amounts, interest rates, dates, and business information you enter never get transmitted to any server, stored in any database, or tracked. Your financial data stays completely private on your device.