Hong Kong has a trap that no other jurisdiction in this series has.
The Inland Revenue Department prints a field labelled "TIN" on the Tax Return for Individuals and on Notices of Assessment. A Hong Kong taxpayer opens their tax return, sees a number literally called TIN, and gives it to their bank.
That number is not the TIN.
The IRD says so directly:
the "TIN" shown on the Tax Return-Individuals and related Notice of Assessment is not a TIN equivalent of a Hong Kong tax resident for AEOI purposes. Such "TIN" is solely used for login onto "eTAX" account provided by the Department.
It is a portal login credential. Here is what the real answer is, in the exact format the forms expect.
The correct answer
| You are | Your Hong Kong TIN |
|---|---|
| An individual Hong Kong tax resident | HKID number, all letters and numerals, without the brackets |
| An entity | The first 8 numerals of the Business Registration certificate number |
Both come straight from the IRD's AEOI guidance. Neither is the number printed as "TIN" on a tax return.
The IRD prints it, and it serves one purpose: logging in to eTAX.
- Not valid for CRS self-certification
- Not what a bank onboarding form means
- The label is the whole trap
Every letter and digit, with the brackets removed.
- Keep the check character, drop the brackets
- Accepted for CRS and bank forms
- For an entity, use the first 8 digits of the BR number instead
For individuals: the HKID, reformatted
The IRD's wording is precise:
The TIN equivalent for individuals includes all letters and numerals of the HKID number, including the letter or numeral in the bracket (but without bracket).
An HKID is printed on the card with a check character in brackets. The TIN drops the brackets and keeps the character.
| On the card | As a TIN |
|---|---|
X123456(A) | X123456A |
AB123456(7) | AB1234567 |
Two details that cause rejections.
Keep the check character. It is part of the number, not punctuation. Dropping it produces a different, wrong identifier.
Remove the brackets. Many bank and platform validation routines reject any non-alphanumeric character in a TIN field.
Hong Kong IDs carry either one or two leading letters, which is why field lengths vary between people. A form that demands a fixed length is wrong.
For entities: the first 8 digits of the BR number
The IRD again:
The TIN equivalent for entities includes 8 numerals at the front of BR certificate number.
The Business Registration certificate number is longer than eight digits. Only the first eight constitute the TIN.
This is where Hong Kong's two-number system starts to bite, so it is worth being explicit about which number you are cutting down.
| Number | Issued by | Role |
|---|---|---|
| Business Registration number | Inland Revenue Department | ✅ Its first 8 digits are the entity TIN |
| Company number (CR number) | Companies Registry | ❌ Not the TIN |
⚠️ This depends on when the company was incorporated. Since 27 December 2023 the Companies Registry has used the Business Registration Number as the Unique Business Identifier, so a company incorporated on or after that date shows the BRN on its Certificate of Incorporation, and there is no separate 7 digit company number.
| Incorporated | On the Certificate of Incorporation | Is it the basis of the TIN |
|---|---|---|
| Before 27 December 2023 | 7 digit company number | ❌ No, use the BR certificate |
| On or after 27 December 2023 | 8 digit BRN, as UBI | ✅ Yes, it is the BRN |
For an older company, take the number from the Business Registration Certificate, not from the Certificate of Incorporation.
Why Hong Kong ended up here
Hong Kong never created a dedicated tax identifier. It adopted two numbers that already existed: the identity card number for people, and the business registration number for businesses.
That is the same approach Singapore took, and it usually works well. The complication is that the IRD separately built an eTAX portal, and gave the login credential for that portal the name TIN.
So Hong Kong has a number called TIN that is not the TIN, and two numbers that are the TIN but are called something else.
What the form is actually asking for
Financial institutions in Hong Kong collect TINs under the Common Reporting Standard, the OECD framework for automatic exchange of financial account information.
The institution reports account information to the IRD, which passes it to the tax authority of the jurisdiction where you are tax resident. The number identifies you to that authority, which is why the form asks for a jurisdiction of tax residence alongside it.
The consequence: the number must be the one your tax authority recognises. An eTAX login credential is meaningless to a foreign revenue service.
If you are not a Hong Kong tax resident
Common situation, and one the SERP handles badly.
You hold a Hong Kong company but live elsewhere. A bank asks for your TIN.
Two different questions are being asked, and they have different answers.
| Question | Answer |
|---|---|
| The entity's TIN, as a Hong Kong tax resident entity | First 8 digits of the BR number |
| Your personal TIN | The TIN of your country of tax residence, not Hong Kong's |
A non-resident individual with no HKID has no Hong Kong TIN. The form wants your home jurisdiction's number in your personal section, and the Hong Kong entity's BR-derived number in the entity section.
Filling a personal TIN field with the company's BR number is a common and consequential error.
| What to enter | |
|---|---|
| Entity section, Hong Kong company | The first 8 digits of the Business Registration number |
| Personal section, Hong Kong tax resident | The HKID number, without brackets |
| Personal section, not a Hong Kong tax resident | The TIN of your own country of tax residence, not a Hong Kong number |
| Any section, in every case | Never the “TIN” printed on the tax return or the assessment notice |
Where to find each number
| Number | Where |
|---|---|
| HKID | On your Hong Kong identity card |
| Business Registration number | On the Business Registration Certificate, displayed at the company's premises |
| Company number (not the TIN) | On the Certificate of Incorporation |
The Business Registration Certificate is renewed every one or three years. The number itself does not change on renewal, so an old certificate still gives you the right eight digits.
If a Hong Kong company cannot produce its Business Registration Certificate, that is a question in itself. Displaying it at the place of business is a requirement, not a courtesy.
Common mistakes
Using the eTAX login "TIN". The one the IRD explicitly excludes. The most common error, and the reason this article exists.
Keeping the brackets on the HKID. X123456(A) will fail validation on many forms. Use X123456A.
Dropping the check character. It belongs to the number.
Using the company number instead of the BR number. Different issuer, different purpose, not the TIN.
Using the full BR certificate number. Only the first eight digits.
Putting the entity number in the personal TIN field. Two sections, two different questions.
How Hong Kong compares
| Jurisdiction | Individuals | Entities | Trap |
|---|---|---|---|
| Hong Kong | HKID, no brackets | First 8 digits of BR number | ⚠️ A field called TIN that is not the TIN |
| Singapore | NRIC or FIN | UEN | None |
| Estonia | Personal identification code | Registrikood | None |
| United Kingdom | NINO | ⚠️ UTR or CRN, official sources differ | High ambiguity |
| Ireland | PPS number | Tax reference number | Low |
| United States | SSN or ITIN | EIN, no public register | No public lookup |
Hong Kong's answer is unambiguous once you know it. The problem is purely that an official document uses the term for something else.
The summary
| You want to | Answer |
|---|---|
| Give a TIN as a Hong Kong tax resident individual | ✅ HKID, brackets removed, check character kept |
| Give a TIN for a Hong Kong entity | ✅ First 8 digits of the BR number |
| Use the number labelled TIN on your tax return | ❌ Explicitly excluded by the IRD |
| Use the company number from the Certificate of Incorporation | ❌ Not the TIN |
| Give a Hong Kong TIN as a non-resident individual | ❌ You have none; give your own jurisdiction's |
| Get a separate TIN certificate | ❌ No such document |
Frequently asked questions
What is the tax identification number in Hong Kong?
For individuals, the Hong Kong Identity Card number, including all letters and numerals and the character shown in brackets, but written without the brackets. For entities, the first eight numerals of the Business Registration certificate number.
Is the TIN on my Hong Kong tax return the right one?
No. The IRD states that the "TIN" shown on the Tax Return for Individuals and related Notice of Assessment is not a TIN equivalent for AEOI purposes, and is used solely to log in to the eTAX account.
How do I format my HKID as a TIN?
Remove the brackets and keep the character inside them. An HKID printed as X123456(A) is written X123456A.
What is the TIN for a Hong Kong company?
The first eight numerals of the Business Registration certificate number, issued by the Inland Revenue Department. Not the company number from the Companies Registry.
Is the company number the same as the Business Registration number?
No. The company number comes from the Companies Registry and identifies the legal entity. The Business Registration number comes from the Inland Revenue Department and identifies the taxable business. Only the second one produces the TIN.
I own a Hong Kong company but live abroad. What is my TIN?
The company's TIN is derived from its Business Registration number. Your personal TIN is the one issued by your own country of tax residence. A non-resident with no HKID has no Hong Kong TIN.
Do I need to apply for a Hong Kong TIN?
No. There is no application and no certificate. The number already exists on your identity card or on the company's Business Registration Certificate.
Why does my bank ask for a TIN?
Hong Kong participates in the Common Reporting Standard. Financial institutions collect tax identification numbers and jurisdictions of tax residence so account information can be reported to the IRD and exchanged with foreign tax authorities.
Does the BR number change when the certificate is renewed?
No. Business Registration Certificates are renewed every one or three years, but the number itself stays the same, so an older certificate still gives you the correct eight digits.
Sources
- IRD: Residency for tax purposes and Taxpayer Identification Number (TIN)
- IRD: Automatic Exchange of Financial Account Information
The TIN equivalents for individuals and entities, the formatting rules and the statement about the TIN printed on tax returns are quoted directly from the Inland Revenue Department's AEOI guidance, consulted in August 2026. This is informational, not tax advice.