On 26 October 2026, the Inland Revenue Department announced that the Pillar Two Portal now supports filing of the top-up tax return. A Part 4AA entity of an in-scope multinational enterprise (MNE) group for a fiscal year beginning on or after 1 January 2025 can file the return electronically and view or download electronic notices of top-up tax assessment. This note summarises public IRD materials for Hong Kong businesses, group tax and company secretarial teams — general information only, not tax advice.
Based on the IRD What’s New item and the dedicated GMT / HKMTT webpage. Confirm scope, deadlines and filing steps against the latest official guidance and your advisors.
What changed
The Pillar Two Portal is the Commissioner-designated system for Part 4AA entities to submit top-up tax notifications and returns in electronic form. It is an extended function of the Business Tax Portal (BTP). Per the IRD, the Portal now helps entities to:
- file annual top-up tax notifications relating to return-filing obligations;
- file annual top-up tax returns (BIR82); and
- view and download notices of top-up tax assessment as the filing entity.
The dedicated webpage on global minimum tax (GMT) and Hong Kong minimum top-up tax (HKMTT) has been updated with further filing information, user guides and e-demos.
Who may be affected (high level)
GMT and HKMTT mainly apply to in-scope MNE groups — broadly those with consolidated revenue of EUR 750 million or more in at least two of the four fiscal years immediately preceding the current fiscal year. Hong Kong implements the rules from 2025. The top-up tax return must be filed electronically through the Pillar Two Portal; paper filing is not accepted.
In general, the ordinary return filing deadline is 15 months after the end of the reporting fiscal year, extended to 18 months for the group’s transition year for filing purposes. A top-up tax notification is generally due within 6 months after the last day of the reporting fiscal year; filing the notification typically triggers issuance of the return.
Practical tips (SMEs / company secretaries / cross-border groups)
- Confirm whether you are in scope — many local SMEs will not meet the EUR 750m threshold, but Hong Kong members of large groups, JVs or related entities should verify Part 4AA status with group tax early.
- Register or update BTP business accounts — notifying entities need dedicated BTP accounts to access the Portal. Assessment notices and payment vouchers (if any) are issued only electronically to BTP accounts — not on paper.
- Authentication and agents — authorised signatories must use an organisational e-cert with AEOI functions. Service providers and tax representatives can access the Portal for clients once managed through BTP.
- Align with mandatory profits tax e-filing — Part 4AA entities of in-scope groups are generally required to e-file profits tax returns from year of assessment 2025/26 (with a “once-in, always-in” feature). Diary both calendars together.
- Group codes — filing a notification may require the IRD-assigned MNE / JV group code; apply early using Form IR1485 (paper).
Suggested next steps
- Confirm in-scope status, Hong Kong entity list and any designated local / paying entity appointments
- Check BTP accounts, organisational e-cert (AEOI) and service-agent permissions
- Diary notification (~6 months) and return (generally 15 / transitional 18 months) deadlines alongside profits tax e-filing
- Use only official IRD / Pillar Two Resource Centre channels — ignore phishing emails claiming to be from the IRD
Sources: IRD What’s New (26 Oct 2026) · 稅務局最新消息 · GMT / HKMTT page (EN) · 全球最低稅／香港最低補足稅專頁 · Pillar Two Portal FAQs