How to File the Hong Kong Profits Tax Return (BIR51)

The Profits Tax Return (PTR) is the annual filing through which a Hong Kong business reports its assessable profits, or adjusted loss, to the Inland Revenue Department (IRD). For a limited company, the relevant form is BIR51. The IRD uses it, together with the audited financial statements and tax computation attached to it, to assess how much profits tax the company owes for the year of assessment.

Hong Kong taxes on a territorial basis: profits tax applies to profits arising in or derived from Hong Kong from a trade, profession or business carried on in Hong Kong. If your company claims that some or all of its profits are offshore sourced, that claim is made through this same filing, supported by evidence. We cover it in detail in our guide to the Hong Kong offshore profits tax exemption.

One confusion trips up almost every first-time Hong Kong director, so let us clear it immediately.

Every corporation carrying on a trade, profession or business in Hong Kong must file a Profits Tax Return when the IRD issues one. The IRD sends out the annual bulk issue of returns at the start of April each year, and from 1 April 2026 it issues Notices to File Profits Tax Returns (Form IRC1952 for corporations) as part of its move to the electronic Business Tax Portal.

The core rule is simple: the return must be filed within 1 month of the issue date. In practice, most established companies do not file on that timetable, because of the Block Extension Scheme.

The Block Extension Scheme

Companies represented by a tax representative benefit from extended deadlines that depend on the company’s accounting year-end date, grouped under the codes N, D and M. The extensions can push the effective date out by several months, which is one reason most Hong Kong companies appoint an accounting firm as tax representative. We keep the full deadline table by year-end code in our Hong Kong accounting compliance guide, alongside the rest of the annual compliance calendar.

The first Profits Tax Return: the 18-month rule

A newly incorporated company does not receive a return in its first April. The IRD typically issues the first Profits Tax Return about 18 months after the date of incorporation or commencement of business, and grants around 3 months to file it, reflecting a longer initial basis period and a first audit. Do not mistake this delay for an absence of obligation: profits earned from day one are all reportable on that first return, and the first audit usually takes longer than founders expect.

A company chargeable to profits tax that does not receive a return remains obliged to notify the IRD of its chargeability. Silence from the IRD is not an exemption.

For corporations, the BIR51 does not travel alone. It must be filed together with the company’s financial statements for the basis period, audited by a Hong Kong practising Certified Public Accountant where an audit is required, and a tax computation with supporting schedules showing how the assessable profits, or adjusted loss, were calculated from the accounting profit.

An important rule change catches out companies relying on older guidance. Before 2023, small corporations with gross income not exceeding HK$2 million could file the BIR51 without attaching their supporting documents. That concession ended. Since the 2022/23 year of assessment, a corporation with any gross income in the basis period must submit the Profits Tax Return together with all supporting documents, including financial statements and the tax computation, regardless of the amount of gross income and the filing mode.

The requirement is triggered by having gross income in the basis period, and it removes the old HK$2 million small-corporation concession. Formally dormant companies under the Companies Ordinance are excepted, as explained next.

On the audit itself, Hong Kong offers no small company audit exemption. The audited financial statements requirement applies in all cases except three: companies formally declared dormant under the Companies Ordinance (Cap. 622), companies incorporated in a jurisdiction whose laws do not require an audit and where no auditor’s report has been prepared, and Hong Kong branches of foreign companies that supply certain information with the return.

Our compliance guide covers the audit requirement, and the reporting exemption that is often confused with it, in full.

Hong Kong corporations are taxed under the two-tiered profits tax regime: 8.25% on the first HK$2 million of assessable profits, and 16.5% on assessable profits above HK$2 million. For unincorporated businesses filing BIR52, the corresponding rates are 7.5% and 15%.

The regime comes with an anti-fragmentation rule that matters to founders running several entities: among connected entities, only one can elect the two-tiered rates for a given year of assessment. Connected entities broadly cover companies under common control, so splitting a business across multiple Hong Kong companies does not multiply the HK$2 million reduced-rate band. The election is made in the return, and the connected-entities position is declared through the relevant supplementary form.

Supplementary forms are part of the Profits Tax Return and report information on preferential regimes and tax incentives, starting with Form S1 for the two-tiered rates and connected entities. Whichever way you file the BIR51 itself, all applicable supplementary forms must be completed and submitted electronically through the IRD’s electronic filing services under the Business Tax Portal or Tax Representative Portal. If the return is filed on paper, a signed Control List (Form IR1477) covering the e-filed supplementary forms is furnished with it.

When the IRD assesses your return, it usually charges provisional profits tax for the following year of assessment, estimated on the current year’s profits. The provisional amount is typically payable in two instalments and is credited against the final liability once the next return is assessed.

If your profits are expected to fall significantly, or you have grounds such as a loss year, the company can apply to hold over all or part of the provisional tax before the payment deadline. For cash flow planning, treat the notice of assessment as two obligations in one: the final tax for the year just filed and a prepayment on the next.

Failing to file a Profits Tax Return on time, or filing an incorrect return, is an offence under the Inland Revenue Ordinance. The headline exposure is a fine of up to HK$10,000, and the court may order the outstanding return to be filed within a specified time. Beyond the fine, the practical consequences are often costlier:

• Estimated assessments. If no return is filed, the IRD can issue an estimated assessment of the company’s profits, frequently higher than reality, shifting the burden onto the company to object within the statutory window and prove its actual position.
• Additional tax and prosecution. Understating profits or making incorrect statements can attract additional tax by way of penalty, and in serious cases prosecution with substantially higher exposure, including penalties calculated by reference to the tax undercharged.
• A compliance record. A company that files its Profits Tax Return, Employer’s Return and Companies Registry filings late as a pattern invites closer scrutiny from every direction.

The dependable way to stay clear of all of it is unglamorous: a tax representative on the Block Extension Scheme, an audit that starts before the return arrives, and both the filing and payment deadlines in the calendar.

This guide is based on the Inland Revenue Department’s official guidance, verified in August 2026: Completion of Profits Tax Returns and Supplementary Forms (bus_cpt.htm), the Profits Tax Return filing requirements, and iXBRL Filing. Rates and requirements reflect the position published by the IRD as at August 2026.

Tax rules and filing arrangements evolve, particularly with the IRD’s transition to the electronic tax portals; always confirm current requirements on ird.gov.hk or with a Hong Kong tax representative before filing.