Part 4AA entities of in-scope MNE groups can now file top-up tax returns and download assessment notices electronically, while paper filing is no longer accepted.
Hong Kong’s Inland Revenue Department (IRD) has launched new functions on its Pillar Two Portal from 26 October 2026. A Part 4AA entity of an in-scope MNE group can now file a top-up tax return and view and download notices of top-up tax assessment electronically.
The functions apply to fiscal years beginning on or after 1 January 2025. A Part 4AA entity is a member of an MNE group that falls within the scope of Hong Kong’s global minimum tax rules.
No more paper returns
The department has updated its guide on global minimum tax and Hong Kong minimum top-up tax for multinational enterprise groups. Its section on tax compliance and administration now states that the top-up tax return (BIR82) must be filed electronically through the Pillar Two Portal. No paper filing will be accepted.
A sample BIR82 and the Notes and Instruction to BIR82 have been published to help filers.
What entities can do on the portal
A Part 4AA entity of an in-scope MNE group must file a top-up tax notification and a top-up tax return as an electronic record, using a system designated by the Commissioner. The enhanced portal allows Part 4AA entities to:
- file annual top-up tax notifications relating to their obligations of filing top-up tax returns;
- file annual top-up tax returns; and
- view and download the notices of top-up tax assessment by the filing entity.
Registration and deadline
The Pillar Two Portal is an extended function of the Business Tax Portal (BTP). Entities required to file top-up tax notifications for MNE groups (notifying entities) must first register dedicated business accounts under the BTP. This gives them direct access to the Pillar Two Portal.
Notifying entities must file the top-up tax notification online within six months after the last day of the reporting fiscal year. In general, filing the notification triggers the issue of the top-up tax return.
Authentication requirements
Individuals authorised to sign and submit top-up tax notifications and top-up tax returns on behalf of notifying entities and filing entities must use their e-cert (Organisational) with AEOI Functions. The certificate is used for authentication.
Electronic notices and payment vouchers
Notices of top-up tax assessment and payment vouchers (if applicable) will be issued electronically. They will go to the BTP Business Accounts of the relevant filing entities and assessed entities.
Since no notice of assessment or payment voucher will be issued on paper, assessed entities must also hold dedicated BTP Business Accounts when the top-up tax return is filed. This includes designated paying entities. The same requirement applies to joint venture groups.
Who else can use the portal
Certain parties may access the portal’s online services for or on behalf of a Part 4AA entity. They are collectively referred to as “Service Agent” and include:
- a service provider engaged under section 13 of Schedule 63 to the IRO;
- a tax representative appointed for the purposes of global minimum tax and Hong Kong minimum top-up tax; and
- a person acting for or managing the non-corporate Part 4AA entity.
BTP Administrator(s) can manage Service Agents through the BTP.
Where to find help
The department has set up a Pillar Two Resource Centre with user guides and an e-demo for the portal. Further details on registering a BTP Business Account and managing Service Agents are available on the department’s website. Information on applying for an e-cert (Organisational) with AEOI Functions can be found on the Hong Kong Post website.
Groups within scope of the global minimum tax rules should ensure their entities have the required accounts and certificates in place before the first filing deadline.
