The 30-day deadline, and why it is unforgiving
Filing the return is only half the job, it has to be verified, and the clock is short. Since 1 August 2022 the verification window is 30 days from the date of filing, cut down from the old 120 days. If you verify within the 30 days, your return counts as filed on the original date. If you verify late, the return is treated as never filed at all, and you have to file and verify again, with the new date now the filing date. If that later date falls after the due date, you have effectively filed a belated return, which brings a late fee, interest, and the loss of your right to carry forward capital losses. So for an NRI, verification is not an afterthought, it is a deadline as real as the filing date itself.
The reason this trips up NRIs specifically is the default method. Residents usually verify in seconds with an Aadhaar one-time password, but that needs an Aadhaar linked to an Indian mobile number, and most NRIs have neither an Aadhaar nor a live Indian SIM. So the Aadhaar route is usually closed to you, and you need to know the alternatives before the 30 days run down.
The methods that work from abroad
Four electronic methods work without an Indian mobile. The smoothest is net-banking: log in to your Indian bank's net-banking, find the income-tax e-filing link, and it verifies the return instantly. Second, an electronic verification code, or EVC, can be generated from a bank account that you have pre-validated and enabled on the tax portal, and an NRO or NRE account works for this. Third, the same EVC can come from a demat account. Fourth, a digital signature certificate signs and verifies the return, and an NRI can obtain one using foreign-address documents such as a passport and overseas address proof, usually attested or apostilled.
If none of the electronic methods is open to you, there is still the paper fallback: print the ITR-V acknowledgement, sign it in blue ink, and send it by ordinary or speed post to the Centralised Processing Centre in Bengaluru so it arrives within the 30 days, and posting it from a foreign address is accepted. One point of confusion worth clearing up: a digital signature is only compulsory where your accounts have to be audited under the tax-audit rules, for example a large business turnover. For an ordinary NRI with a property sale, salary or capital gains, a digital signature is optional and net-banking or a bank EVC is enough. A practising CA files and verifies the return for you and makes sure the 30-day window is not missed.