Most Hong Kong companies have filed their profits tax return on paper for as long as there has been a return. That is starting to change. The Inland Revenue Department (IRD) has committed to the full adoption of electronic filing for corporations and unincorporated businesses, excluding sole proprietorships, and the first phase is already law [1]. Here is who is caught now, what the IRD expects an e-filer to send, and what a business outside the first phase should do in the meantime. Every date and threshold below is taken from an IRD page and linked to it.
| Item | What applies | Source |
|---|---|---|
| First phase: years covered | Profits tax returns for a year of assessment beginning on or after 1 April 2025, that is 2025/26 onwards | [1] |
| First phase: returns covered | Profits Tax Return, Corporations (BIR51) and Profits Tax Return, Persons Other Than Corporations (BIR52) | [1] |
| First phase: who is in scope | An entity that is a Part 4AA entity of an MNE group (condition 1) whose group is, or for an earlier fiscal year beginning on or after 1 January 2025 was, an in-scope MNE group (condition 2) | [1] |
| In-scope MNE group | Annual consolidated revenue of EUR 750 million or above in at least two of the four fiscal years immediately preceding the current fiscal year | [1] |
| Later phases | By phases, starting with large businesses first and then progressing to entities of smaller scale; the pages cited here give no start date for a second phase | [2] |
| Sole proprietorships | Excluded from the IRD's plan for full adoption of profits tax e-filing | [1] [2] |
| Once in scope | "Once-in, always-in": e-file for every subsequent year, even if the conditions stop being met | [1] |
| Filing format | Return through the Business Tax Portal or Tax Representative Portal; financial statements and tax computation in iXBRL under the IRD Taxonomy Package, unless an exception applies | [3] |
| Supplementary forms | All required supplementary forms (S1 to S22) electronically, whatever the mode of filing the return | [3] |
| Due date on the e-filing notice | Within 2 months from the date of issue of the Notice to File Profits Tax Return | [5] |
| Extra time for mandatory e-filers | A further 1 month after the block extension date or the normal due date, whichever is later | [5] |
| Extra time for voluntary e-filers | A further 1 month on application, received at least 7 working days before the return is otherwise due | [5] |
| Paper still allowed, first phase | Among other exceptions: a 2025/26 return issued on or before 31 March 2026, or a 2026/27 return issued on or before 31 March 2027 | [1] |
Who must e-file now
The first phase came with the global minimum tax. The Inland Revenue (Amendment) (Minimum Tax for Multinational Enterprise Groups) Ordinance 2025 amended section 51AAB of the Inland Revenue Ordinance and added Schedule 65 so that entities of in-scope multinational enterprise (MNE) groups must e-file their profits tax returns for a year of assessment beginning on or after 1 April 2025, that is 2025/26 onwards [1].
An entity is caught only if it meets both of two conditions [1]:
- Condition 1: it is a Part 4AA entity of an MNE group for the fiscal year corresponding to the year of assessment. That covers a Hong Kong constituent entity, a Hong Kong standalone joint venture, a Hong Kong member of a joint venture group, and a Part 4AA stateless constituent entity.
- Condition 2: its MNE group is an in-scope MNE group for that fiscal year, or was one for an earlier fiscal year beginning on or after 1 January 2025.
An in-scope MNE group is one with annual consolidated revenue of EUR 750 million or above in at least two of the four fiscal years immediately before the current one [1]. If that is not your group, the first phase does not apply to you. The mandate covers both forms of profits tax return: the BIR51 for corporations and the BIR52 for persons other than corporations, such as partnerships [1].
The rule is "once-in, always-in". An entity that has had to e-file for one year must e-file for every later year, even if it leaves the group or the group drops below the threshold [1]. There is a short list of cases where an entity in scope may still file on paper, including an entity being wound up, one that has notified its cessation, financial statements covering more than 12 months, and a 2025/26 return issued on or before 31 March 2026 or a 2026/27 return issued on or before 31 March 2027. Even then, every required supplementary form still has to be filed electronically [1].
What the later phases look like
The IRD describes the programme as phased: mandatory e-filing will start with large businesses first and then progress to entities of smaller scale, with the ultimate goal of full-scale implementation [2]. The IRD pages cited in this guide set out the first phase in detail but give no start date or revenue test for a second phase, so we do not guess one here. When the IRD announces the next phase it will appear on the same pages; check them each spring before the April bulk issue of returns.
Sole proprietorships sit outside the whole programme. The IRD's stated aim is full adoption of e-filing for corporations and unincorporated businesses excluding sole-proprietorship businesses [1] [2]. A sole proprietor reports business profits on a different form altogether; our guide to the sole proprietor tax return covers it.
What an e-filer sends, and in what format
Electronic filing is not a scan of the paper return. Through the Business Tax Portal (BTP) or the Tax Representative Portal (TRP), a business files the return itself and attaches the required supplementary forms, the financial statements and the tax computation with supporting schedules [3]. The IRD's process has three services, used in order [3]:
- Uploading Service: supplementary forms are prepared in the latest fillable PDF versions and exported as XML data files; financial statements and the tax computation are uploaded in inline eXtensible Business Reporting Language (iXBRL) in accordance with the IRD Taxonomy Package, unless an exception applies.
- Completion Service: the return is completed online and saved as a draft for submission.
- Submission Service: an authorized signer checks, signs and submits it, then saves or prints the Acknowledgement.
Uploaded iXBRL files are validated, and the result is released within one working day. A file that fails validation is not treated as attached to the return until the errors are fixed and it is uploaded again [3]. Uploading alone is not filing: unless the completed return is submitted, the filing obligation has not been met [3].
You do not need to buy software to produce iXBRL. The IRD publishes a Taxonomy Package and free iXBRL Data Preparation Tools, and released updated versions of both on 1 April 2026 [2]. The IRD also encourages businesses to adapt their own programs to generate the files [2].
Some of this applies to everyone already. All required supplementary forms, S1 to S22, must be submitted electronically whatever the mode of filing the return [3], and a business with gross income must file its return with all supporting documents, including financial statements and the tax computation; small businesses with gross income not exceeding HK$2 million can no longer file without them [7].
Registering for the Business Tax Portal
The BTP is the IRD's multi-user portal for businesses. Once registered, a business can submit tax returns online, view returns it has e-filed and assessments issued, and correspond with the IRD [4]. Only the business's Responsible Person can open the BTP Business Account. For a corporation that is a director, company secretary, liquidator or provisional liquidator, or, for a non-Hong Kong company, its authorized representative in Hong Kong; for a partnership, a partner [4].
The Responsible Person proves their identity with iAM Smart, an Individual Tax Portal login or a personal digital certificate, and appoints BTP Administrators, no more than five per account. Administrators then appoint Authorized Users and assign each the services they may use [4]. To file a profits tax return, a user needs "Profits Tax Matters" [3]. A business without a BTP account can still use the Uploading Service with the file number and Return Identification Number (RIN) printed on its paper return, but cannot complete or submit the return that way [3].
If an accountant acts for you, it works through the TRP. A tax representative on the IRD's record for profits tax can upload and complete the return for you, and a service provider you appoint to furnish the return can also submit it, provided it has obtained your Confirmation for Engagement of Service Provider to Furnish Return (IR1476) [3].
Deadlines and the extra month
For a taxpayer in the first phase, the IRD sends a Notice to File Profits Tax Return instead of a paper return, through the message box of its BTP Business Account or by post if it has no BTP account yet, and the return is due online within 2 months from the date of issue of the Notice [5]. The Block Extension Scheme applies as usual for represented taxpayers, and on top of it the IRD extends the deadline of an entity subject to mandatory e-filing by a further 1 month, counted from the day after the block extension date or the normal due date of the e-return, whichever is later [5].
That further month is automatic only for entities that told the IRD of their status before March 2026; an entity in scope that has not, and still receives a paper return for 2025/26, has to ask for it [5]. A business e-filing voluntarily can also get a further 1 month, on application received at least 7 working days before the return would otherwise be due [5] [3]. The block extension dates themselves, by accounting date code, are in our profits tax return guide.
If your business is not in scope yet
Nothing changes for your filing method this year: you may file on paper, or e-file voluntarily. The IRD encourages businesses outside the mandate to e-file voluntarily now, both to get ready for the later phases and for the extra month [2] [7]. Voluntary e-filing through the BTP or TRP is open for years of assessment 2022/23 to 2025/26 [3].
What does change is the evidence. Your return still needs a full set of financial statements and a tax computation, and when your phase arrives those will have to be tagged in iXBRL. The tagging is mechanical once the accounts are final; what takes the time is getting the accounts final. A business that closes its books monthly, with every bank line matched to a document, can produce the statements and the computation from the same figures every year, in whatever format the IRD asks for.
E-filing a profits tax return, step by step
- Check whether your company is in scope. Who: the company's directors, with the group's finance team if it belongs to a group. By when: before the return is due, and again each year, because the test looks at the group's revenue across the preceding fiscal years [1]. A 2025/26 BIR51 or BIR52 now asks the same question in items 3.9 to 3.9.1 of BIR51 and 2.8 to 2.8.1 of BIR52 [6].
- Open a Business Tax Portal (BTP) Business Account. Who: the Responsible Person: for a corporation, a director, company secretary, liquidator or authorized representative; for a partnership, a partner [4]. By when: well before filing season. The Responsible Person verifies their identity with iAM Smart, an Individual Tax Portal login or a personal digital certificate, then appoints up to five BTP Administrators [4].
- Appoint whoever will prepare and sign. Who: the BTP Administrators, who appoint Authorized Users with "Profits Tax Matters"; or a tax representative or service provider working through the Tax Representative Portal [3]. By when: before the Notice to File arrives. A service provider who signs for you must first obtain your Form IR1476 [3].
- Prepare the financial statements and tax computation in iXBRL. Who: the company, its tax representative, or its own software; the IRD offers free iXBRL Data Preparation Tools [2]. By when: once the accounts are final. Uploaded files are validated, with the result given within one working day, so leave time to fix errors [3].
- Upload, complete and submit through eTAX. Who: an authorized signer: for a BIR51, a director, secretary or manager; for a BIR52, the precedent partner, among others [3]. By when: within 2 months from the date of issue of the Notice, plus any block extension and the further month mandatory e-filers receive [5]. Save or print the Acknowledgement afterwards [3].
How Suma handles this
Suma is accounting software, not a tax filer, and it does not produce iXBRL files or send anything to the IRD. It keeps the books the financial statements and the tax computation are built from, so they are ready whichever way the return goes in:
- Double-entry books with 4-digit account codes, where every edit is a void and a re-create, so the history behind each figure stays visible.
- A bank feed through Finverse that brings business bank lines into the books as they happen.
- Receipts and documents vaulted against the books, so each entry can be traced to its source document.
- A year-end pack exported to our partner CPA firm, with more than 40 years in practice, under a hash the server computes, so the firm can show the pack it worked from is the pack that was sent.
- A filed year locked against edits, so the figures behind a return cannot drift after it is filed.
- Auditor questions answered on your request desk, line by line, with the receipt attached.
Frequently asked questions
Is profits tax e-filing mandatory in Hong Kong?
Only for some businesses so far. From year of assessment 2025/26, a Hong Kong entity of a multinational group with consolidated revenue of EUR 750 million or more in two of the four preceding fiscal years must e-file its BIR51 or BIR52 [1]. The IRD plans to extend the requirement by phases to smaller businesses, but has not published a date for the next phase on the pages cited here [2]. Everyone else may still file on paper.
How do I e-file a profits tax return with the IRD?
Open a Business Tax Portal Business Account through your Responsible Person, appoint administrators, and give the person preparing the return "Profits Tax Matters" access [4] [3]. Then use the three services in order: upload the supplementary forms and the iXBRL financial statements and tax computation, complete the return online, and sign and submit it [3]. A tax representative or service provider can do this for you through the Tax Representative Portal [3].
Does a small company need iXBRL to file its profits tax return?
Not unless it e-files. A small company outside the first phase can still file a paper return, with its financial statements and tax computation attached on paper [1] [7]. If it chooses to e-file, the financial statements and tax computation are uploaded in iXBRL under the IRD Taxonomy Package, unless an exception applies [3], and the IRD's iXBRL Data Preparation Tools are free [2]. Supplementary forms must be filed electronically either way [3].
What is the deadline for e-filing a profits tax return?
For a business in the first phase, the Notice to File sets a due date within 2 months from its date of issue, extended by the Block Extension Scheme where a tax representative acts, and then by a further 1 month for mandatory e-filers [5]. A business e-filing voluntarily can apply for a further 1 month, at least 7 working days before the return is otherwise due [5]. The block extension dates by accounting date code are in the IRD's circular [5].
General information current as of 16 October 2026. This is not tax, legal or accounting advice. The IRD publishes later phases of mandatory e-filing as it sets them; confirm the current position with the IRD or a licensed practitioner.