The comparison is arithmetic, not opinion
The new regime offers lower slab rates with almost no deductions. The old regime has higher rates but allows the deductions most salaried taxpayers are used to claiming.
Which is cheaper depends entirely on how much you actually claim — not on how much you could claim in theory. Compute both on your own figures before deciding; anything else is guesswork.
What tips the balance
The old regime usually wins where you have significant 80C investments, health insurance under 80D, house rent allowance you genuinely pay, and home loan interest.
The new regime usually wins where your deductions are modest, your rent is low or you own your home outright, and you would rather not lock money away to save tax.
Switching between them
If you have only salary, pension, house property or capital gains income, you can choose afresh each year while filing.
With business or professional income the choice is exercised through Form 10-IEA and switching back is restricted, so it has to be planned rather than decided at filing time.
The mistake to avoid
Choosing a regime in April, telling your employer, and never revisiting it. Your income and your claims change during the year, and your employer's TDS follows the declaration you gave — not the position that ends up being correct.
Review it mid-year. The final choice is made when you file, and a mismatch simply means a larger refund or a larger payment than necessary.
This is general information, not advice for your case.
Figures and dates apply to the financial year stated in the article and can change by notification. Bring your own position to a consultation and we will confirm what actually applies.