Form BIR51: Hong Kong corporation profits tax return

What Is Form BIR51

Form BIR51 is the profits tax return the Inland Revenue Department issues to Hong Kong corporations. It is the primary document for reporting a company's assessable profits for a year of assessment. The IRD sends Form BIR51 to active corporations shortly after each year of assessment ends. The return is due within one month of its date of issue.

Corporations use the form to declare profits or losses for the relevant basis period, calculate tax payable under the two-tiered rates, and attach audited financial statements and a tax computation. A corporation with no assessable profits must still file the return and report a nil result.

Form BIR51 Hong Kong

Form BIR51 is for Hong Kong corporations only. Unincorporated businesses file Form BIR52; non-resident persons file Form BIR54. The IRD issues the return based on a company's business registration record and filing history. A newly incorporated company receives its first Form BIR51 18 months after incorporation, covering the period from incorporation to its chosen accounting reference date.

Profits Tax Return Corporations

The profits tax return is how a company reports income, claims deductions, and calculates its tax liability. The return covers the basis period, which is usually the company's financial year ending in the year of assessment. A company with a 31 December year end files a return for the year of assessment 2025-26 covering the period 1 January 2025 to 31 December 2025.

Corporations must attach audited financial statements and a tax computation showing how assessable profits were derived. The IRD may also request supporting schedules, such as a revenue breakdown by source or details of capital allowances claimed.

IRD Form BIR51

The IRD issues Form BIR51 as part of its annual tax filing cycle. The form is pre-printed with the company's name, business registration number, and the year of assessment. The IRD sends the return to the company's registered office address, or to an appointed tax representative.

Each year the IRD publishes a block extension letter setting later filing dates for companies with a tax representative. These extension dates depend on the company's accounting date. Companies with a 31 December year end may have a filing deadline of August or September of the following year, instead of the standard one-month deadline.

Hong Kong Corporate Tax Return

The Hong Kong corporate tax return is Form BIR51. It is the only form corporations use to file their profits tax return. The return is accompanied by supplementary forms S1 to S18, required when the corporation has specific types of income or claims. Supplementary form S2 reports income from intellectual property, and supplementary form S9 reports a claim for the two-tiered profits tax rate.

These supplementary forms are part of the return and must be completed accurately. Failing to attach the correct supplementary form can delay processing or trigger a request for more information.

BIR51 Filing Requirement

Every corporation that receives Form BIR51 must file it, even if the company made a loss or had no business activity. A dormant company that has not declared itself dormant to the Companies Registry must still file. A company that has ceased trading must file a final return covering the period up to the date of cessation.

This filing requirement applies regardless of any tax liability. Failure to file by the deadline may result in an estimated assessment from the IRD, which is typically higher than the actual liability, plus penalties and surcharges.

A director, the company secretary, or an authorised tax representative must sign the return. Electronic filing through the Business Tax Portal requires the authorised person to use their digital signature or log-in credentials. Financial statements and tax computation must be tagged in iXBRL format for electronic filing; the IRD provides preparation tools.

Provisional tax is assessed alongside the profits tax return. The IRD issues a notice of assessment for the current year's profits tax and a provisional tax notice for the following year, based on the assessable profits reported. A corporation may apply to hold over all or part of the provisional tax if it expects profits to fall in the next year.