The law
Income-tax Act 1961, Sec 139(1) (now Sec 263(1)), Explanation 2 as substituted by Finance Act 2026
Due date 31 August for business or profession not required to be auditedSource
Income-tax Act 1961, Sec 44AD (now Sec 58)
Turnover up to ₹2 crore (₹3 crore if cash receipts are 5% or less); income at 6% of digital and 8% of other receipts, or moreSource
Income-tax Act 1961, Sec 44ADA (now Sec 58)
Professional receipts up to ₹50 lakh (₹75 lakh if cash is 5% or less); income at 50% of receiptsSource
Income-tax Act 1961, Sec 44AE (now Sec 58)
Goods carriage income on presumptive basis, up to 10 vehiclesSource
Income-tax Act 1961, Sec 115BAC(1A) (now Sec 202) and Form 10-IEA
New regime is default; business filers opt out by Form 10-IEA on or before the Sec 263(1) (old Sec 139(1)) due dateSource
Income-tax Act 1961, Sec 234F (now Sec 428)
Late fee ₹1,000 or ₹5,000 by incomeSource
Government fee
No filing fee. Tax due is paid as self-assessment tax via e-Pay Tax before filing. Source: https://www.incometax.gov.in/iec/foportal/help/all-topics/e-filing-services/itr-4/itr-4-UM
Late fee or penalty
After 31 August: Sec 428 (old Sec 234F) fee ₹1,000 (total income up to ₹5,00,000) or ₹5,000; Sec 423 (old Sec 234A) interest 1% a month on unpaid tax; the old regime option is not available in a late return with business income. Source: https://www.incometax.gov.in/iec/foportal/help/all-topics/e-filing-services/%20income%20tax%20returns-faq and https://calcguru.in/belated-return-after-due-date/