Income Tax Return Filing in Nepal: Deadlines, Penalties, and What Gets Missed

The date that matters is Ashwin end. Not Ashad end, when the fiscal year closes, and not some round figure like 30 September that a foreign parent company's finance team assumes by habit. Nepal's income tax return is due roughly three months after the fiscal year closes, and the three months are counted in the Nepali calendar, which means the actual Gregorian cut-off shifts by a day or two each year. Businesses that copy last year's deadline into this year's calendar without checking the Miti conversion are already exposed before they have filed anything.

Prepared by Nishant Marasini and team · Position stated as at 22 September 2026

Nepal runs its fiscal year from Shrawan 1 to the end of Ashad — mid-July to mid-July in Gregorian terms. Every return, every installment schedule, every audit selection cycle at the Inland Revenue Department is built around that calendar, not the January-to-December year most foreign investors and even many Nepali sole proprietors instinctively think in. Get the fiscal year wrong in your own bookkeeping and everything downstream — installments, the return, the assessment — inherits the error.

The filing deadline, and where it actually sits

Under the Income Tax Act, 2058, a resident person is required to file the annual income tax return within three months of the end of the income year — that is, by Ashwin end, which falls in mid-to-late October depending on the year. IRD can grant an extension on application, and in practice does, particularly for taxpayers with statutory or group audit requirements that are not yet complete by the deadline. That extension is not automatic and is not indefinite; it is typically capped and must be applied for before the original deadline lapses, not after. Waiting until Ashwin end to discover that the audited financials are not ready is the single most common way businesses end up filing late rather than filing on extension.

The deadline also is not uniform across every taxpayer category in practice. Taxpayers under presumptive or turnover-based taxation, entities filing estimated returns, and large taxpayers under the Large Taxpayers Office face different administrative rhythms even though the statutory three-month window is the common anchor. Do not assume your subsidiary's deadline matches your competitor's simply because both are private limited companies — the applicable IRD office and the taxpayer category both affect what's expected and when.

Advance tax is not the annual return — and it has its own deadlines

This is where businesses that are otherwise diligent still get caught. Nepal requires most taxpayers to pay income tax in installments during the year, not just as a lump sum after year end. These advance tax (installment) payments are due at three points in the fiscal year — the standard structure requires 40 percent of estimated annual tax liability by Poush end, a cumulative 70 percent by Chaitra end, and the remaining balance to 100 percent by Ashad end. Each of those is a separate statutory deadline with its own exposure to interest if missed, entirely independent of whether the annual return itself is filed on time in Ashwin.

A company can file its annual return perfectly on 15 Ashwin and still owe interest for the year because the second installment in Chaitra was three weeks late. The annual return does not cure a missed installment; it only reports what happened. Businesses that treat "tax season" as a single event clustered around the return deadline consistently miss this — the installment obligations sit five and eight months earlier in the same fiscal year, calculated on an estimate of that year's own liability, which itself has to be revised if the business's performance changes materially during the year.

What the penalty structure generally looks like

Late filing and late payment carry separate consequences, and both apply concurrently — filing late does not substitute for paying late, and paying in full without filing the return does not stop the filing penalty from running. The general architecture, largely unchanged in shape across recent Finance Acts even though the specific rates and fee amounts are revised through the annual budget, is a fee for late filing of the return calculated on a percentage-of-tax or fixed-amount basis (whichever the current Finance Act specifies), plus interest that accrues monthly on any unpaid tax from the date it was due, plus a separate penalty exposure if IRD determines the shortfall arose from understatement rather than mere delay. Because these rates move with each year's budget, the operative figures should always be checked against the Finance Act currently in force for that fiscal year rather than assumed from a prior year's experience — a business that budgets for last year's penalty rate on the assumption nothing changed is guessing, not planning.

Interest on unpaid installments and on unpaid final tax compounds the cost of delay in a way that is easy to underestimate when cash flow, not compliance, is driving the decision to defer payment. A business that consciously delays an installment because of a temporary liquidity problem is making a financing decision, and should price it as one — compare the effective interest cost against the cost of a short-term facility — rather than treating it as a free deferral.

Three things that consistently get missed on self-filed returns

Businesses that prepare their own returns without a structured pre-filing review tend to miss the same handful of things, year after year.

1. TDS certificates never reconciled against declared income

Every payment made to a business that is subject to tax deduction at source generates a TDS certificate from the payer, and the cumulative TDS withheld across the year is meant to be credited against the recipient's final tax liability. In practice, many businesses declare their income from sales and services without separately pulling together every TDS certificate they were issued during the year and checking that the income underlying each certificate actually appears in the books at the matching amount. Where a customer withheld tax on a payment that was recorded net, or where a certificate was never received at all despite tax having been withheld, the business either understates its income or overstates its TDS credit — both of which IRD's own cross-matching against the payer's TDS return can surface later, well after the return has been filed and accepted.

2. Advance tax installments tracked as an afterthought

As above — because the installment deadlines sit in Poush, Chaitra, and Ashad, well before the return itself is due, businesses that build their tax compliance calendar around the Ashwin filing date alone are structurally missing three earlier obligations. The fix is mechanical: the installment schedule needs to sit in the same calendar as the return deadline, with its own estimate of annual liability revisited at each of the three checkpoints rather than fixed once at the start of the year.

3. Expense deductions without supporting documentation that survives assessment

An expense recorded in the books is not the same as an expense IRD will allow on assessment. Deductions claimed for items such as staff costs paid in cash, purchases from unregistered vendors, entertainment and representation expenses, or related-party charges are routinely disallowed where the taxpayer cannot produce contemporaneous supporting documentation — invoices that meet the required particulars, proof of payment through a traceable channel, and, for related-party transactions, evidence that the pricing reflects an arm's-length basis. Businesses often discover this gap only when an assessment officer asks for the file two or three years after the return was filed, by which point reconstructing the paper trail is far harder than it would have been to maintain it contemporaneously. Self-filed returns claim the deduction; they rarely stress-test whether the deduction would survive an assessment.

The practical takeaway

The return itself is a summary. The exposure sits in three places that are each earlier and less visible than the Ashwin deadline: whether the installments were paid on the dates the Act specifies, whether every TDS certificate received actually matches the income declared, and whether the expense file could be handed to an assessment officer today without gaps. A business that gets those three right rarely has a difficult return season, regardless of how the filing deadline itself moves from year to year.