80C is now Section 123. Here is the part nobody is telling you.

If you have filed a return in India in the last fifteen years, you know what 80C means without having to think about it. It is the ₹1.5 lakh. It is the reason you have an ELSS you never look at and a life insurance policy somebody sold you in March.

That number is gone. Not the deduction - the number. From 1 April 2026 the Income-tax Act, 2025 replaced the 1961 Act, and every deduction section was renumbered along the way.

Most of what you will read about this change is a lookup table. Useful, and we keep one of those too. But a table cannot tell you the part that will actually cost people money this year, which is not the new number at all. It is the date.

The date that decides which number you use

Here is the trap. The Act came into force on 1 April 2026. That is a fact about the law, not about your return. The return you sit down to file in mid-2026 covers the year that ended on 31 March 2026 - and that year is still governed by the Income-tax Act, 1961.

The Act changed in April. Your next return did not.

So the return you file in 2026 says 80C, because the year it describes was an 80C year. The first return that says Section 123 is the one you file in 2027, covering Tax Year 2026-27. If you spend this filing season hunting for Section 123 in the utility, you will not find it, and you will conclude something is broken when nothing is.

What actually merged, and why it matters

The renumbering was not a find-and-replace. Section 123 absorbed two other sections: the old 80CCC, for pension fund contributions, and the old 80CCD(1), your own contribution to NPS.

Those three always shared one ₹1.5 lakh ceiling. That was true under the 1961 Act too - it just took a cross-reference to see it. Plenty of people read three sections and assumed three buckets. The 2025 Act removes the ambiguity by putting them in one place.

Nothing about that arithmetic changed in April 2026. What changed is that it is now hard to get wrong by accident, because there is one section number to look up instead of three.

The ₹50,000 that really is extra

There is one NPS deduction that genuinely sits on top, and it is the one people most often leave unclaimed: the old Section 80CCD(1B), now Section 124. Its ₹50,000 is additional to the ₹1.5 lakh, not inside it.

The catch that undoes all of it

Every deduction above is old-regime only. Section 123 does not exist for you if you are on the new regime - Section 202, formerly 115BAC - and the new regime is the default. You have to actively choose the old one.

Under the new regime, the deductions that survive are the standard deduction on salary and the employer’s NPS contribution. Your PPF, your ELSS, your insurance premium: none of them reduce your taxable income.

Which means the renumbering is genuinely irrelevant to a large number of salaried people, and the honest thing to do is check which of the two you are before you spend a weekend reorganising investments around a section that does not apply to you.

The rest of the renumbering, briefly

80C is the one everyone knows, but the whole Chapter VI-A moved. The ones a salaried person is most likely to meet:

The full table, including the housing sections and the ones where the mapping is confirmed by only a single published source, is on our Income-tax Act 2025 section finder. It is searchable by the old number, the new number, or the thing you are actually trying to claim.

What this actually is

A renaming, done carefully, of a system whose numbers had accumulated letters and brackets for sixty years. The money did not move. The ceilings did not move. What moved is that a provision people navigated by memory now has to be navigated by reading, at least for a year or two until the new numbers become the ones you know without thinking.

The mistake worth avoiding is not using the wrong number. It is assuming the change means something changed about what you owe. For nearly everyone, it does not.