Guidelines for Submitting Income Tax Return under Section 139(1)

Every taxpayer in India eventually runs into one question: do I actually have to file an income tax return this year? The answer usually starts and ends with Section 139(1) of the Income Tax Act, 1961. This provision lays down the basic rule of who must submit a return of income, by when, and under what circumstances someone can be made responsible for filing on behalf of another person. For B.Com students studying tax law, this section is the foundation for everything else in the “Filing of Returns” unit, because almost every later provision – belated returns, revised returns, defective returns – builds on what Section 139(1) sets up first.

What section 139(1) actually says 🔗

In plain terms, Section 139(1) requires every company and firm to file a return of income every year, regardless of profit or loss. For individuals, Hindu Undivided Families (HUFs), Associations of Persons (AOPs), and Bodies of Individuals (BOIs), the obligation kicks in only when total income exceeds the basic exemption limit – the threshold below which no tax is payable at all. The section also covers a second, less obvious category: a person who is assessable as a representative assessee, meaning someone who must file and pay tax on income that legally belongs to another person.

Who must file a return under section 139(1) 🔗

Companies and firms – no exceptions 🔗

This is the simplest rule in the entire section. A company or a firm, including a Limited Liability Partnership, must file its return whether it made a profit, incurred a loss, or had no business activity at all during the year. There is no minimum income threshold for these entities.

Individuals, HUFs, AOPs, and BOIs – the exemption limit test 🔗

For everyone else, the trigger is the basic exemption limit, and this figure depends on which tax regime applies. Since the new tax regime became the default option, the exemption limits look like this for the financial year 2025-26:

It is worth noting that under the new regime, a rebate under Section 87A effectively makes income up to ₹12 lakh tax-free for resident individuals, but this rebate does not remove the obligation to file – it only reduces the tax payable to zero. Filing is still governed by gross total income before deductions, not the final tax liability.

The seventh proviso – mandatory filing despite low income 🔗

Here is where many students trip up: income below the exemption limit does not always mean filing is optional. A provision inserted through the Finance Act, 2019, known as the seventh proviso to Section 139(1), forces certain people to file a return even when their taxable income is nil, if they have carried out specific high-value transactions during the year.

Meeting even one of these conditions is enough to make filing compulsory, as explained in this detailed breakdown of the seventh proviso. The idea behind this rule is straightforward: the tax department wants a paper trail wherever large sums of money move, even if the person’s calculated tax liability happens to be zero.

Filing on behalf of someone else – representative assessees 🔗

Section 139(1) does not assume that every taxpayer is capable of filing their own return. Some people cannot – a minor, a person of unsound mind, a non-resident earning income in India, or someone who has passed away. In these cases, the law shifts the responsibility to a representative assessee: a guardian, agent, legal heir, or trustee who steps in and files the return on the principal’s behalf.

The Income Tax Department’s e-filing portal has a formal mechanism for this. A person can register as a legal heir or representative assessee by submitting proof of relationship, such as a legal heir certificate, power of attorney, or guardianship document, along with the PAN details of both parties. Once approved, the representative can file, verify, and manage returns exactly as the original assessee would have. This same logic extends to trustees of charitable or religious trusts, who must file returns on behalf of the trust whenever its income before exemption exceeds the basic limit, as required under a related sub-section of the same law.

Due dates you cannot afford to miss 🔗

Section 139(1) does not just say who must file – it also fixes the deadline. For the financial year 2025-26 (assessment year 2026-27), the applicable due dates are as follows:

These dates are drawn from the official filing timeline for AY 2026-27, and they shift slightly almost every year depending on government notifications, so it is worth checking the Income Tax Department’s portal closer to the filing season rather than relying on memory.

What happens if you miss the section 139(1) deadline 🔗

Missing the due date does not shut the door entirely, but it does make things more expensive and restrictive.

You can still file a belated return 🔗

Section 139(4) allows a belated return to be filed after the due date, but before three months prior to the end of the relevant assessment year, or before the assessment is completed, whichever comes first. For FY 2025-26, this window closes around 31 December 2026.

A late fee applies under Section 234F 🔗

Filing after the due date attracts a penalty of up to ₹5,000 under Section 234F, reduced to ₹1,000 if total income does not exceed ₹5 lakh. On top of this, interest under Section 234A accrues on any unpaid tax for the period of delay.

Losses cannot be carried forward 🔗

This is the consequence students often underestimate. If a return showing a loss under the heads “Capital Gains” or “Profits and Gains of Business and Profession” is filed after the due date, that loss cannot be carried forward to set off against future income. A loss under “House Property,” by contrast, can still be carried forward even if the return is filed late – one of the specific exceptions worth remembering for exams.

Why timely filing matters beyond compliance 🔗

Filing on time under Section 139(1) is not purely a legal formality. A return filed within the due date is often required as proof of income for loan applications, visa processing, and government tenders. It is also the only route to claiming a refund of tax that has already been deducted at source. Voluntary filers – people whose income is below the exemption limit but who file anyway – often do so precisely for these practical reasons, even though the law does not force them to.

What do you think? If income tax law already exempts people below the basic threshold from filing, should the seventh proviso’s high-value transaction rule be expanded further, or does it already strike the right balance between catching tax evasion and avoiding unnecessary compliance burden on genuinely low-income taxpayers? And from a fairness standpoint, does it make sense that a late-filed capital loss cannot be carried forward while a late-filed house property loss can?

References

1. https://www.incometaxindia.gov.in/w/section-139-1
2. https://cleartax.in/c/income-tax-slab-rates
3. https://taxguru.in/income-tax/mandatory-income-tax-return-seventh-proviso-section-1391-income-tax-act-1961.html
4. https://www.incometax.gov.in/iec/foportal/help/all-topics/e-filing-services/Managing-your-Account/Register-as-Legal-Heir
5. https://setupfiling.in/section-1391-of-the-income-tax-act/
6. https://tax2win.in/guide/section-139-of-income-tax-act