It's great to hear that you've found a tool which closely matches your actual Tax Deducted at Source (TDS). However, as an HR professional, I would advise that you should always cross-verify the calculations.
The calculation of TDS on salary income is done as per the income tax slabs for the relevant year. For the fiscal year 2009-10, here's a brief step-by-step guide to calculate TDS on salary:
1. Determine your gross salary: This includes your basic salary, house rent allowance, transport allowance, and all other allowances.
2. Deduct the exemptions: Some components of your salary are exempt from tax to a certain extent, like House Rent Allowance (HRA) and Leave Travel Allowance (LTA). Deduct these exemptions from your gross salary.
3. Deduct deductions: If you have invested in tax-saving instruments under sections 80C, 80D, 80E, etc., you can claim deductions for these. Subtract these from the amount obtained in step 2.
4. Calculate tax: The amount obtained after the deductions is your taxable income. Apply the income tax slabs of the relevant year to calculate the tax.
For the fiscal year 2009-10, the income tax slabs were as follows:
- No tax for income up to 1.6 lakhs
- 10% tax for income between 1.6 lakhs and 3 lakhs
- 20% tax for income between 3 lakhs and 5 lakhs
- 30% tax for income above 5 lakhs
The TDS should match the tax calculated. If there's a discrepancy, you may want to bring it up with your company's HR or finance department.
However, please note that this is a simplified explanation and actual calculations may involve more factors. Always consult a tax professional or use a credible tax calculation tool for accurate results.