For twenty years, a Hong Kong company had two numbers. Most guides still say so.
On 27 December 2023 that stopped being true for new companies.
The Companies Registry adopted the Business Registration Number as the Unique Business Identifier, and a company incorporated since that date has one number, not two. Older companies still carry both.
So the answer to "which number do I need" now depends on when the company was formed. Here is the rule, and what it changes in practice.
The rule, by date of incorporation
| Incorporated | Numbers it has | On the Certificate of Incorporation |
|---|---|---|
| Before 27 December 2023 | Two: a 7 digit company number and an 8 digit BRN | The 7 digit company number |
| On or after 27 December 2023 | One: the 8 digit BRN, serving as the UBI | The 8 digit BRN |
Both regimes coexist and will for decades. A 2015 company and a 2025 company are documented differently, and neither is wrong.
- Before 27 Dec 2023The Certificate of Incorporation carries a 7-digit company number from the Companies Registry, and the Business Registration Certificate carries a separate 8-digit BRN from the Inland Revenue Department. Two issuers, two numbers.
- 27 December 2023The Business Registration Number is adopted as the Unique Business Identifier.
- SinceA newly incorporated company receives one 8-digit BRN, shared by both authorities. There is no separate 7-digit company number to look for.
The two numbers, and who issues them
| Business Registration Number | Company number | |
|---|---|---|
| Issued by | Inland Revenue Department | Companies Registry |
| Length | 8 digits | 7 digits |
| Appears on | Business Registration Certificate | Certificate of Incorporation, pre-2023 companies |
| Identifies | The taxable business | The legal entity |
| Who must have one | Every business in Hong Kong | Only incorporated companies |
| Renewed | Every 1 or 3 years | Never, permanent |
| Basis of the tax identification number | ✅ Its first 8 digits | ❌ No |
That last row is the one that matters most on international forms, and it did not change in 2023. The entity TIN for Hong Kong is derived from the Business Registration Number, whichever certificate that number happens to appear on.
What the Unique Business Identifier changed
Before December 2023, two Hong Kong government bodies each maintained their own identifier for the same company. Bank forms asked for one, invoices carried the other, and nobody was sure which a given counterparty wanted.
The UBI reform made the BRN the single identifier used across the Companies Registry and the Inland Revenue Department.
Three practical consequences.
New companies are simpler. One number on the incorporation certificate, the same number on the business registration certificate, the same number everywhere else.
Old companies keep both numbers. Nothing was reissued. A company incorporated in 2010 still has its 7 digit company number and its separate 8 digit BRN.
Entities without a BRN got a placeholder. Some entities incorporated before 27 December 2023 were exempt from registration under the Business Registration Ordinance and therefore had no BRN. Those were assigned a "dummy" BRN with an alphabetic prefix by the Registry, so that every entity has a UBI.
If you meet a Hong Kong identifier with a letter at the front where you expected eight digits, that is what you are looking at. It is not a data error.
The BRN format, and the part people cut wrongly
A Business Registration Number is often written with more than eight digits.
12345678-001
The first eight digits are the BRN itself. What follows after the hyphen is the branch number.
000 or 001 is the main business; higher numbers are registered branches.
| Written as | The BRN | The rest |
|---|---|---|
12345678-000 | 12345678 | Main business |
12345678-002 | 12345678 | Second registered branch |
Two consequences.
On a tax form, use the first eight digits only. The IRD is explicit that the entity TIN equivalent is the eight numerals at the front of the BR certificate number.
On a bank form, give what the form asks for. Some want the full string including the branch suffix, because they are identifying a specific registered location.
Which number a form actually wants
| Situation | Number |
|---|---|
| CRS or FATCA self-certification, entity section | First 8 digits of the BRN |
| Tax filing with the IRD | BRN |
| Filing with the Companies Registry | Company number, or the BRN for post-2023 companies |
| Bank account opening | Usually the BRN, often the full string with branch suffix |
| Invoices | BRN |
| Supplier onboarding by an overseas counterparty | BRN, and expect them to call it a company number |
| Verifying a company in the registry search | Either works; the company number is stable for old companies |
The reliable instinct: when in doubt, the BRN. It is the number every Hong Kong body now uses, and it is the one an overseas counterparty is most likely to be able to match.
The certificate you must display
This is a legal obligation and a useful diligence signal.
Every business operating in Hong Kong, whether a limited company, a sole proprietorship, a partnership or a branch, must obtain a Business Registration Number within one month of starting business, and must display the valid certificate at the place of business.
So the BRN is not a private reference. A legitimate Hong Kong business has it on the wall.
If a Hong Kong counterparty cannot produce a current Business Registration Certificate, you have learned something. Renewal is annual or three-yearly, so an expired certificate is also informative: the business has stopped maintaining its registration.
When neither number finds the company
You have a BRN and the registry search returns nothing. Registry search works on company names and company numbers. For an older company the BRN is not the registry identifier. Search the name instead.
You have a 7 digit number and the company is recent. Post-2023 companies do not have one. You are probably holding a truncated BRN.
The entity is a sole proprietorship or partnership. It has a BRN and no company number, because it was never incorporated. It will not appear in the Companies Registry at all.
It is a non-Hong Kong company with a Hong Kong presence. Registered separately as a registered non-Hong Kong company, and since December 2023 its Certificate of Registration also carries the BRN as its UBI.
How Hong Kong compares now
| Jurisdiction | Identifiers per entity | Single number across agencies |
|---|---|---|
| Singapore | 1 UEN | ✅ Yes |
| Estonia | 1 registrikood | ✅ Yes |
| Hong Kong, since Dec 2023 | 1 BRN as UBI | ✅ Yes, for new entities |
| Hong Kong, before Dec 2023 | 2 | ❌ |
| Ireland | CRO number plus tax reference | ❌ |
| United Kingdom | 5 candidates, 3 issuers | ❌ |
Hong Kong has quietly joined Singapore and Estonia in the clean group. The transition is what creates the confusion, not the destination.
The summary
| You want to | Answer |
|---|---|
| Know how many numbers a HK company has | ✅ One if formed since 27 Dec 2023, two if before |
| Know which is on the incorporation certificate | ✅ BRN for new companies, 7 digit company number for old |
| Get the entity TIN | ✅ First 8 digits of the BRN |
| Know what follows the hyphen | ✅ The branch number, not part of the BRN |
| Understand a letter-prefixed identifier | ✅ A dummy BRN assigned to a pre-2023 exempt entity |
| Verify a counterparty | ✅ Ask for the Business Registration Certificate, which must be displayed |
| Search the registry by BRN | ⚠️ Works for new companies; search by name for older ones |
Frequently asked questions
When did Hong Kong merge the two numbers?
On 27 December 2023, when the Companies Registry adopted the Business Registration Number as the Unique Business Identifier for all entities it administers.
Does my old Hong Kong company get a new number?
No. Companies incorporated before 27 December 2023 keep both their 7 digit company number and their 8 digit BRN. Nothing was reissued.
How long is a Hong Kong business registration number?
Eight digits. It is often written with a hyphen and three further digits, which are the branch number rather than part of the BRN.
What does the number after the hyphen mean?
The branch number. 000 or 001 identifies the main business, and higher numbers identify registered branches.
Which number do I put on a CRS form?
The first eight digits of the Business Registration Number. The Inland Revenue Department states that the entity TIN equivalent is the eight numerals at the front of the BR certificate number.
Why does some Hong Kong identifier start with a letter?
Entities incorporated before 27 December 2023 that were exempt from business registration had no BRN, so the Registry assigned them a dummy BRN with an alphabetic prefix so that every entity has a UBI.
Do sole proprietorships have a company number?
No. They hold a Business Registration Number but were never incorporated, so they have no company number and do not appear in the Companies Registry.
Does a Hong Kong business have to display its certificate?
Yes. Every business must obtain a BRN within one month of starting business and display the valid certificate at its place of business. That makes the certificate easy to request from a counterparty.
Does the BRN change when the certificate is renewed?
No. Business Registration Certificates are renewed every one or three years, and the number stays the same throughout.
Sources
- Companies Registry: Unique Business Identifier
- GovHK: business registration
- IRD: Residency for tax purposes and Taxpayer Identification Number (TIN)
The adoption of the Business Registration Number as the Unique Business Identifier from 27 December 2023, and the treatment of entities without a BRN, reflect the Companies Registry's published implementation. Number formats and the display obligation reflect the Business Registration Ordinance and IRD practice as published in August 2026. Verify with the Companies Registry and the IRD before relying on this for a filing.