What should a taxpayer do if income shown in Form 26AS mismatches?

If income is mismatched in Form 26AS, a taxpayer should first compare it with bank statements, invoices, and other records. They can also contact the deductor, such as company, buyer of goods or another entity, and ask them to verify the details and file correction statement. If the issue remains unresolved, taxpayers can raise grievance through Income Tax e-filing portal.