The structural difference
Both regimes tax the same salary; they differ in what you subtract first and at what rates the remainder is taxed. The old regime rewards documented deductions and exemptions. The new regime removes most of them and compensates with wider, lower slabs.
That means the comparison is really about one question: how large are the deductions you genuinely claim, not the ones you could theoretically claim?
Make an honest deduction list
Before comparing, write down what you actually claim each year with proof — retirement contributions, insurance premiums, housing interest, rent-based exemption, education or medical items relevant to you. Include only amounts you can substantiate.
- If that list is large relative to your salary, the old regime often wins.
- If you claim little beyond the standard items, the lower slabs of the new regime usually win.
- Borderline cases are common, and the gap is often small enough that simplicity matters.
Compute, do not estimate
Slab structures, rebates and surcharge thresholds interact in ways that are hard to eyeball. Enter your salary and deductions once and read the tax under both regimes side by side, including cess. Do this at the start of the financial year, because your declaration drives monthly tax deducted from salary — discovering a shortfall in the final quarter is the expensive way to learn.
Things that change the answer
A large rent-based exemption, a home loan in its interest-heavy early years, or a jump in income across a threshold can all flip the comparison. Revisit the calculation whenever your salary structure, rent or loan changes, and confirm anything unusual with a qualified professional or the official tax portal before filing.