A Business Number, sometimes called a CRA Business Number or simply a BN, is a unique nine-digit identifier the CRA assigns to a business — the number that CRA program accounts, such as GST/HST and payroll, are attached to. Understanding what it actually is clears up a lot of confusion about when and why registration is needed.

What Is a Business Number, Exactly?

A Business Number is a nine-digit number the CRA assigns to identify a business in its dealings with the federal government. It's not itself a tax account — once a BN exists, CRA program accounts such as GST/HST, payroll, and corporation income tax are identified using that BN plus an applicable program identifier and reference number added on top of it.

Does Every Business Need a Business Number?

A sole proprietor operating under their own name, with no employees and not registered for GST/HST, generally doesn't need to register for a Business Number, since they can report business income on their personal tax return using their Social Insurance Number. A Business Number is generally required when a business registers for certain CRA program accounts — most commonly GST/HST, payroll, or corporation income tax — rather than something a business independently needs on its own.

How a Business Number Gets Assigned

A BN can be registered on its own or at the same time as certain CRA program accounts, depending on the business's circumstances, through the CRA's Business Registration Online service. CRA's Business Registration Online process has changed recently — as of July 14, 2026, BRO is accessed through a CRA account rather than as a standalone service — so it's worth checking CRA's current registration instructions directly before starting rather than relying on a remembered process.

Why Incorporation Usually Results in a Business Number

Incorporating a business generally results in a Business Number being created for the new corporation, since a corporation is a distinct legal entity that needs its own CRA identification. Corporations incorporated federally or in most provinces — including Ontario and BC — are automatically assigned a BN and corporation income tax account as part of that process, since those incorporation registries share information directly with the CRA. Quebec works differently — a Quebec corporation registers with Revenu Québec and receives a separate Quebec Enterprise Number (NEQ), a distinct provincial identifier that is not the same as, and doesn't replace, a federal CRA Business Number.

What the Business Number Actually Gets Used For

Once assigned, the Business Number appears on GST/HST registration, payroll accounts, corporate tax filings, and correspondence with the CRA — it's the constant thread connecting all of a business's different CRA accounts, which is why it needs to be readily available whenever setting up a new program account or contacting the CRA about an existing one.

Registering for GST/HST is one of the most common reasons a Business Number gets created in the first place, though not every sole proprietor needs GST/HST registration simply because they're operating a business — which makes it worth confirming whether that registration is actually required before applying for anything. RSB's GST/HST quiz is the place to check.

FAQ

Does a Business Number expire or need to be renewed? No — once assigned, a Business Number stays with the business permanently, even if specific program accounts under it are later closed.

Can a business have more than one Business Number? Generally, no — a business or legal entity can only have one BN. Multiple CRA program accounts, such as GST/HST, payroll, and corporation income tax, are attached to that same BN using different program identifiers and reference numbers.

What happens to the Business Number if a sole proprietorship incorporates later? Incorporating creates a new legal entity, and a new Business Number is automatically assigned to the corporation. This is a common bookkeeping trap: the existing GST/HST or payroll accounts under the old sole proprietor BN don't automatically transfer to the new one. Those old accounts generally need to be closed separately, and the same program accounts re-registered under the corporation's new BN.

Is a Business Number the same as a GST/HST number? No — a GST/HST account is identified by the nine-digit Business Number followed by a program identifier and reference number, commonly formatted as something like 123456789 RT 0001. The Business Number itself is just the base nine digits; the GST/HST account adds identifying characters on top of it.

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