Hong Kong Profits Tax Return: BIR51 Deadlines and Documents

A Hong Kong limited company must file Form BIR51 by the date set by the Inland Revenue Department. Most issued returns allow one month, while first returns and represented cases can follow different timetables.

Form BIR51 Reports a Corporation’s Profits Tax Position

Form BIR51 is the Profits Tax Return for corporations. The current form cites section 51(1) of the Inland Revenue Ordinance and requires a true and correct return of assessable profits or adjusted loss.

A company must respond when the IRD issues the return, even if it reports a loss, has no tax payable, or claims that income falls outside Hong Kong’s taxing scope.

The filing has a different purpose from the statutory audit and Form NAR1. InvestinAsia’s Hong Kong company audit guide explains the financial reporting work that can support BIR51.

Form NAR1 goes to the Companies Registry and reports company particulars. The Hong Kong NAR1 filing guide covers its separate deadline and requirements.

Your IRD Notice Sets the Actual Filing Date

The correct deadline starts with the issue date and filing date shown on the IRD return. A company’s incorporation anniversary or financial year end cannot replace the date printed on that notice.

General Return Deadline

The 2025/26 BIR51 form requires filing within one month from its issue date. Use the specific date on any return issued outside the annual bulk programme.

First Return Timeline

The IRD’s 2025/26 circular says it generally issues a first Profits Tax Return about 18 months after incorporation. Earlier issue remains possible when the company’s circumstances warrant it.

A first return issued during the year can be filed within three months from its issue date without a separate extension request. The 18-month point concerns issue timing, not the filing deadline.

2025/26 Block Extension Calendar

The Block Extension Scheme applies to qualifying represented cases. The accounting date code follows the company’s financial year end, while eligible electronic filing can add time under the IRD’s conditions.

The March 2026 IRD circular set the D-code paper date at 17 August 2026. The IRD’s July update, reproduced by the Association of Women Accountants (Hong Kong), moved it to 31 August.

The same update moved the eligible electronic filing date to 2 October 2026.

The extra month for voluntary electronic filing requires an application received at least seven working days before the otherwise applicable due date. Certain notified Part 4AA entities receive separate treatment under mandatory e-filing rules.

Foreign founders coordinating the return from abroad can review InvestinAsia’s Hong Kong setup and accounting support.

A Missing Return Does Not Remove the Notification Duty

A company that has become chargeable to Profits Tax may need to notify the IRD even if no return arrives.

The IRD’s first-time taxpayer guidance sets a four-month notification period after the relevant basis period ends.

Provide the company name and Business Registration number when requesting a return. Waiting for the usual first-return cycle can create a filing risk after the company becomes chargeable.

The Filing Package Has Three Main Layers

A BIR51 filing combines the return, filed supporting documents, and records that substantiate the figures. Treating those layers as one document request can leave the tax computation unsupported.

Documents Filed With BIR51

The current BIR51 requires a certified statement of financial position, an auditor’s report where required or otherwise prepared, and a statement of comprehensive income or profit and loss account.

The filing also needs a tax computation with schedules showing how accounting results became assessable profits or adjusted loss. The Notes and Instructions can require further documents for the company’s facts.

The IRD’s completion guidance states that corporations with gross income during the basis period must submit all supporting documents with the return. Check any available exception against the company’s legal status.

Supplementary Forms and the Control List

Supplementary forms report specified matters such as a two-tier election, transfer pricing, foreign-sourced income, or intellectual property income. A company completes only the forms that match its tax position.

The IRD requires applicable supplementary forms to be submitted electronically. A paper BIR51 filing can therefore still need electronic XML uploads and a signed paper Control List generated by the filing service.

Records Kept for Review

Bank statements, invoices, contracts, ledgers, fixed-asset schedules, and evidence for adjustments may support the computation without forming part of every initial submission. Keep them indexed to the relevant figures and claims.

The BIR51 Notes state that business records should be retained for at least seven years after the related transactions, or until the corporation dissolves if that occurs sooner.

E-Filing Rules Changed on 1 April 2026

The first phase of mandatory electronic filing applies from the 2025/26 year of assessment. It covers specified Part 4AA entities within an in-scope multinational enterprise group, subject to available exceptions.

The current BIR51 Notes define the in-scope group threshold by reference to annual consolidated revenue of EUR 750 million or more in at least two of the four preceding fiscal years.

Companies outside that mandatory scope can use the filing modes permitted by the IRD. Electronic filing through the Business Tax Portal combines data upload, return completion, authorised submission, and an acknowledgement record.

Mandatory status and voluntary e-filing extensions follow different conditions. Do not add one month without confirming the applicable notification or extension request.

Reconcile BIR51 Before Submission

Reconcile the return to the financial statements, auditor’s report, and tax computation.

The IRD’s filing tips also require the six-digit Hong Kong Standard Industrial Classification code and the auditor’s practising certificate number where applicable.

Complete every field. The IRD’s BIR51 FAQ instructs filers to enter zero where a requested item has no value. Do not leave the item blank.

1. Confirm the year of assessment, basis period, and accounting date code.
2. Reconcile the return to the signed financial statements and tax computation.
3. Identify every supplementary form required by the company’s transactions and elections.
4. Check the filing mode, XML or iXBRL requirements, signer authority, and extension status.
5. Submit by the confirmed date and retain the acknowledgement, return copy, and uploaded files.

Late Filing Can Trigger an Estimated Assessment and Penalties

The IRD states that failure to submit a return on time can lead to an estimated assessment or penalty action. The company may then need to correct the assessment while also completing the overdue return.

The IRD penalty policy uses percentage loading scales for failure to notify chargeability or file on time. Those scales are guidance, and the outcome depends on the facts and offence history.

File the overdue return, preserve evidence of submission, and review any assessment or penalty notice promptly. Payment dates and objection deadlines need their own calendar entries.

Build the Filing Calendar From Four Dates

A reliable BIR51 calendar records the return issue date, printed filing date, financial year end, and confirmed extension date. Add the audit completion target before the filing deadline so the return has signed figures.

• Save the IRD notice and its envelope or electronic issue record.
• Confirm whether the return is the company’s first BIR51.
• Map the financial year end to the N, D, or M code where the Block Extension Scheme applies.
• Confirm tax representative status and any electronic filing extension.
• Set internal dates for bookkeeping close, audit queries, tax computation, sign-off, and submission.
• Track NAR1, Business Registration renewal, audit, tax filing, and tax payment as separate obligations.

Set the audit completion date before the BIR51 deadline, then assign one owner to the tax computation and submission record. InvestinAsia’s Hong Kong service page outlines support for that workflow.