Form 26AS is narrower — it mainly tracks tax deducted at source (TDS), tax collected at source (TCS), and advance tax payments linked to your PAN. AIS is far broader: it also pulls in mutual fund transactions, dividend income, interest from savings accounts and deposits, and even some high-value purchases reported by banks and registrars.
Before filing your return, it's worth checking both against your own records. If AIS shows income you don't recognise or have already accounted for differently, you can submit feedback directly within the AIS portal to flag the discrepancy — the department does review these corrections rather than automatically treating AIS as final truth.
Mismatches between what you declare and what AIS shows are one of the most common triggers for a tax notice, so a five-minute cross-check before filing can save a lot of back-and-forth later.