A Tax Reverse Engine works backwards from the tax amount already paid to calculate what your business income should be. This is especially useful for income tax practitioners and Chartered Accountants while reconciling challan payments with actual tax liability under Assessment Year 2025-26. Instead of calculating tax from income, this tool calculates income from tax — a unique approach not found in standard calculators.
Section 234A interest applies when you file your Income Tax Return after the due date. It is calculated at 1% per month or part thereof on the tax due, from the due date to the actual date of filing. This tool automatically computes 234A interest based on your filing date and adjusts the total payable accordingly.
Section 234B interest applies when advance tax paid during the financial year is less than 90% of the assessed tax liability. Interest is charged at 1% per month from April 1 of the Assessment Year up to the date of filing the return. This calculator automatically checks whether advance tax paid meets the 90% threshold and computes 234B interest accordingly.
Section 234C interest arises when advance tax instalments are not paid on time during the financial year. The required percentages are 15% by June 15, 45% by September 15, 75% by December 15, and 100% by March 15. Shortfall in each instalment attracts 1% interest for 3 months (1 month for the March instalment). This tool calculates 234C instalment-wise and shows the total interest.
The Old Tax Regime allows deductions under Section 80C up to ₹1,50,000, Section 80TTA up to ₹10,000, and several other sections, making it beneficial for taxpayers with high investments, home loan interest, and insurance premiums. The New Tax Regime offers lower slab rates without most deductions and is suitable for taxpayers with fewer investments. This calculator supports both regimes for business income, salaried individuals, senior citizens, and super senior citizens.
Agricultural income is exempt from income tax under Section 10(1). However, for individuals with both agricultural and non-agricultural income, the partial integration method is used to determine the applicable tax rate. Tax is computed on the total of non-agricultural and agricultural income, then reduced by tax on basic exemption plus agricultural income. This tool correctly applies the partial integration method for accurate results.
Section 139(8A) allows taxpayers to file an Updated Return within 4 years from the end of the relevant Assessment Year. An additional tax of 25% on the aggregate of tax and interest is payable if filed within 12 months. This tool automatically applies the 25% additional tax when the filing date entered is after 31st December 2025, helping practitioners calculate the exact amount payable for updated returns.
Surcharge is an additional tax on income exceeding certain thresholds — 10% above ₹50 lakh, 15% above ₹1 crore, 25% above ₹2 crore, and 37% above ₹5 crore under Old Regime. In the New Regime, surcharge is capped at 25%. Marginal relief ensures that the increase in tax due to surcharge does not exceed the increase in income beyond the threshold. This calculator correctly computes both surcharge and marginal relief for all income levels.