A BN number confuses people who also deal with RC numbers. They serve the same purpose for two different kinds of CAC registration.
What a BN number identifies
A BN number identifies a registered business name: a sole proprietorship or a small partnership trading under a name CAC has approved. It is not a company number.
A limited company gets an RC number instead, issued when CAC incorporates it. The two formats identify different kinds of entity, and one cannot stand in for the other. See what is an RC number for the company side of this.
When CAC issues it
CAC assigns the BN number when it approves the business name registration, after the ₦20,000 registration fee is paid and the application clears. See how to register a business name at CAC for that process from the start.
The number does not change afterwards, even if the business changes address or adds a partner. It stays with the business name for as long as it remains registered.
Registering more than one business name gets you more than one BN number, one for each name. They do not share a number just because the same person owns all of them.
Where it appears on your paperwork
The clearest place to find it is the registration certificate CAC issues on approval. Keep both a paper and a digital copy, since you will need to quote the number repeatedly.
It also appears on Form CAC/BN 06, the form used to file a business name's annual return each year, and on any status report or certified document CAC issues about the business name afterwards.
Looking up a business name on the public search
If you have misplaced your certificate, search the business name on the CAC public search on icrp.cac.gov.ng. This is also how a bank, a client or a partner can check that a business name is genuinely registered.
This article cannot confirm every detail the public search displays. For an official reprint of your certificate, contact CAC directly rather than rely on the search result alone.
Why banks and agencies ask for it
A bank usually asks to see the BN number, from the certificate, before it opens a corporate account for the business name. It is also the reference the tax authority links to when the business applies for its Tax ID.
Quote the BN number exactly as it appears on your certificate wherever you are asked for it. A mistyped digit can send an agency looking up the wrong business name entirely.
Save it in the same place you keep other business records, not only on the certificate itself. A number you can quote from memory saves a search every time a form asks for it.
Browse the CAC registration hub for more on registering and running a business name or a company.