Guide to Hong Kong Tax Electronic Filing and iXBRL Requirements

Hong Kong Tax Electronic Filing and IXBRL Requirements Guide

The Inland Revenue Department is phasing out paper profits tax returns. For the largest multinational groups, Hong Kong tax electronic filing is now mandatory. The mandate starts with the year of assessment 2025-26 and follows the OECD Pillar Two threshold: multinational enterprise groups with consolidated revenue of EUR 750 million or more. The IRD’s goal is full electronic filing by 2030, eventually covering all corporate and non-corporate taxpayers.

This is a change to the method of submission, not the tax base or rates. The content of the return, assessable profits, deductions, and supporting schedules, remains the same.

The Shift to Mandatory Electronic Filing

From 1 April 2026, the IRD requires certain taxpayers to file profits tax returns electronically. The mandate applies to entities that are members of multinational enterprise groups with consolidated revenue of EUR 750 million or more. For these groups, the year of assessment 2025-26 is the first period affected. The IRD has stated its intention to reach full electronic filing by 2030.

Hong Kong IXBRL Requirements

The IRD has adopted the iXBRL (inline eXtensible Business Reporting Language) standard for electronic filing. An iXBRL file embeds machine-readable tags into a human-readable document. When filing through the Business Tax Portal or the Tax Representative Portal, the financial statements and the tax computation must each be tagged in iXBRL.

The IRD provides preparation tools on its website to help create compliant iXBRL files from standard accounting data. Tagging requires mapping each line item in the financial statements and tax computation to a relevant IRD taxonomy element. Common items include turnover, cost of sales, administrative expenses, and assessable profits. The IRD taxonomy aligns with Hong Kong Financial Reporting Standards and the standard profits tax computation layout.

A newly incorporated company must use iXBRL only if it falls within the mandatory electronic filing scope. Otherwise, it may still file on paper for its first returns.

Business Tax Portal Hong Kong

The Business Tax Portal Hong Kong is the IRD’s online platform for taxpayers who file their own returns. The portal supports electronic filing of:

• Form BIR51 (profits tax return for corporations)
• Form BIR52 (profits tax return for persons other than corporations)
• Form BIR54 (profits tax return for non-resident persons)
• Supplementary forms S1 to S18 (where applicable)

Access requires an eTAX account and relevant credentials. The portal guides the user through filing, including uploading the tagged iXBRL files. Users can also view the status of their submitted return and any correspondence from the IRD.

Tax Representative Portal Hong Kong

The Tax Representative Portal Hong Kong is for tax representatives, typically certified public accountants, solicitors, or tax agents, who file on behalf of clients. The portal provides a single dashboard to manage all client filings, including uploading iXBRL files, submitting supplementary forms, and viewing block extension dates.

The block extension scheme applies only to returns filed through this portal. Each year the IRD publishes a block extension letter setting later filing deadlines based on the entity’s accounting date. A company with a 31 December accounting date may have a deadline of May or June instead of the standard one month from the return’s issue date. The tax representative must enrol in the scheme and file through the portal to qualify for the extended deadline.

The portal also supports holdover applications for provisional tax.

Mandatory Electronic Filing Hong Kong 2026

The mandate effective from April 2026 applies only to in-scope multinational enterprise groups. An in-scope entity is a member of a group whose ultimate parent entity has consolidated revenue of EUR 750 million or more in at least two of the four preceding fiscal years. These groups must file their profits tax return for the year of assessment 2025-26 electronically using iXBRL tagging.

The IRD will expand the scope of mandatory electronic filing gradually. Full electronic filing by 2030 will require all corporate taxpayers, including those with simple computations and unincorporated businesses, to file through the portals.

For groups below the EUR 750 million threshold, electronic filing remains voluntary but encouraged. Early adoption helps familiarise taxpayers with the process and preparation tools.

Supplementary Forms and Block Extension

When filing electronically, the taxpayer or representative must include relevant supplementary forms S1 to S18. These forms capture tax computation details, deductions, allowances, and any offshore or FSIE claims. iXBRL tagging applies to the numerical data in these supplementary forms, as well as to the financial statements and core tax computation.

The block extension letter from the IRD sets the filing deadline for returns submitted through the Tax Representative Portal. The deadline depends on the entity’s accounting date. For example:

• A company with a 31 December accounting date (basis period ending 31 December 2025 for year of assessment 2025-26) may have a block extension deadline of 30 June 2026.
• A company with a 31 March accounting date may have a block extension deadline of 31 May 2026.

Check the current block extension letter on the IRD website for the exact dates.

Preparation Tools and Compliance

The IRD provides preparation tools to assist with iXBRL tagging. These include:

• A tagging tool that imports financial statements and tax computations from spreadsheets and applies the appropriate IRD taxonomy tags.
• A validation tool that checks the tagged file for errors before submission.
• A sample file illustrating the correct tagging format.

The taxpayer or representative must ensure the tagged file is accurate and complete. Tagging errors, a misclassified line item or incorrect tax rate, can delay processing or trigger an IRD query.

Timeline and Future Scope

The IRD’s roadmap for electronic filing has two key milestones:

• April 2026: Mandatory electronic filing for in-scope MNE groups (year of assessment 2025-26).
• By 2030: Full electronic filing for all profits tax returns.

The IRD may introduce further requirements before 2030, such as mandatory iXBRL tagging for all taxpayers. The department consults with professional bodies and the business community before implementing changes.

Summary of Key Points

• The electronic filing mandate began on 1 April 2026 for large MNE groups with EUR 750 million or more in consolidated revenue.
• iXBRL tagging is required for the financial statements and tax computation of all electronic filers.
• The Business Tax Portal is for direct filers; the Tax Representative Portal is for agents.
• The block extension scheme applies only to returns filed through the Tax Representative Portal.
• The IRD provides preparation tools to assist with tagging.
• The target of full electronic filing by 2030 will eventually cover all corporate and non-corporate taxpayers.