Written by Maryam Ajorloo, CPA · Reviewed by Behdad Karimi Dermeni, CPA
You registered your business, and now a string of characters like `123456789 RT 0001` is showing up on your Canada Revenue Agency (CRA) correspondence. Nobody explained what the letters mean, whether the RT part is a different number from your business number, or why your accountant keeps asking for "the RT." Here is the whole system in plain language, plus how to register in 2026 now that the rules have changed.
The short answer: a business number (BN) is one 9-digit ID the CRA assigns to your business for life. An RT number is not a separate number. It is your BN plus the program code `RT` plus a 4-digit reference, and it identifies your GST/HST account specifically. So `123456789 RT 0001` is business number `123456789`, GST/HST account number one.
Once your BN is live, every CRA account you open hangs off it, and every one of them wants clean numbers behind it. See how ReInvestWealth keeps your books CRA-ready.
What Is a Business Number (BN) in Canada?
A business number is a unique nine-digit identifier assigned to your business by the Canada Revenue Agency. Think of it as your business's social insurance number: one permanent ID that the federal government uses to recognize you across every program you deal with.
The BN exists to centralize things. Instead of a separate account number for sales tax, another for payroll, and another for corporate tax, you get one root number and the CRA hangs each account off it as a program account.
Three program accounts cover most small businesses:
GST/HST, for charging and remitting sales tax. Register and file it here.
Payroll deductions, once you have employees and start withholding at source. CRA payroll accounts.
Corporate income tax, if you are incorporated. CRA corporation accounts.
Having a BN does not obligate you to register for all of them. You open only the accounts your business actually needs, and you add more later as things change.
What Is an RT Number? CRA Program Codes Explained
This is the part almost nobody explains properly, and it is the source of most of the confusion.
Your full program account number is 15 characters, built in three pieces:
The 9-digit business number. This is you. It never changes, and it is the same across every program account.
A 2-letter program identifier. This says which kind of account it is.
A 4-digit reference number. This says which one, when you have more than one of the same kind.
So in `123456789 RT 0001`, the business is `123456789`, the account type is GST/HST, and it is the first GST/HST account on that BN.
The program codes you will actually run into:
RT is GST/HST. When someone asks for your "RT number" or your "GST number," this is what they mean.
RP is payroll. Your T4 filings and source deductions live here.
RC is corporate income tax. Only incorporated businesses have one.
RM is import/export, needed if you bring goods across the border commercially.
Why the 4-digit reference is almost always 0001. Most small businesses have exactly one of each account type, so the reference defaults to `0001` and you can safely ignore it. It matters when a business runs multiple divisions or multiple separate operations and needs `RT0001` and `RT0002` kept apart. More on that below, because it is also the answer to a question people get wrong constantly.
One practical note: when a client, a supplier, or a government portal asks for your GST/HST number, give them all 15 characters, not just the 9-digit BN. The bare BN does not tell them which account to credit. If you ever need to check that a supplier's GST/HST number is real before claiming an input tax credit on it, the CRA has a free registry lookup.
Why You Need a Business Number
1. You cannot charge sales tax without one
If your business collects GST, HST, QST, or PST, the sales tax account has to hang off a BN. No BN means no RT account, which means no legal way to charge sales tax or to claim back the tax you paid on business purchases.
2. It consolidates everything with the CRA
One number covers every account. When you call, file, or log into My Business Account, you are working from a single identity rather than juggling unrelated reference numbers.
3. Larger clients expect it
Corporate clients and government buyers routinely ask for a GST/HST number before they will set you up as a vendor. An invoice with a valid RT number on it clears accounts payable; one without it often comes back.
4. It is the key to most other doors
Government grants, import/export permits, provincial programs, and most business licensing all key off the BN. Getting it early means you are never the person scrambling for one the week an application closes.
How to Register for a Business Number
Registration is free, and if you qualify to do it online you will have your number in minutes.
Step 1: Confirm you actually need one. You need a BN if you collect GST/HST, have employees, are incorporated, or import and export commercially. If you are self-employed, earning under the small supplier threshold, and operating under your own legal name, you may not need one yet. That threshold is $30,000 in taxable sales in a single calendar quarter or across four consecutive quarters, and it is measured on sales, not profit.
Step 2: Gather your details. Have your business legal name, your business structure (sole proprietorship, partnership, or corporation), your physical and mailing addresses, and a plain description of what your business does. If you are incorporated, have your incorporation details on hand.
Step 3: Set up your CRA account first. This is the step that trips people up in 2026. Business Registration Online now sits behind a CRA sign-in. You will need a CRA user ID and password, a Sign-In Partner (your online banking credentials), or a British Columbia or Alberta provincial partner login. Do this before you start, not halfway through.
Step 4: Register through Business Registration Online. BRO is the CRA's registration portal and the standard route for everyone. It creates your BN, opens whichever program accounts you ask for, and confirms both instantly.
Step 5: Open the program accounts you need. You can request your RT, RP, or RC accounts during the same session. If you only need the BN today, that is fine, and you can add accounts later without starting over.
If you cannot register online, Form RC1 is the paper fallback. It is intended for specific cases: you have never filed a Canadian tax return (newcomers, for example), you have not filed in the last two years, or you cannot meet the CRA account sign-in requirements. Paper takes weeks rather than minutes, so treat it as the exception.
That is the whole registration process, and the books that follow are the part that actually takes ongoing effort. See what ReInvestWealth automates.
What Changed in 2025 and 2026
If you are working from older advice, two things are now out of date, and both matter.
Phone registration is gone. As of November 3, 2025, the CRA no longer registers new business numbers or program accounts over the phone. Calling the Business Enquiries line will get you directed to the online portal. Plenty of guides still list "call the CRA" as one of three ways to register. It is not one of them anymore.
BRO now requires a CRA account. As of July 14, 2026, Business Registration Online is only reachable after you sign in. That means CRA credentials, a Sign-In Partner, or a British Columbia or Alberta provincial partner login. Previously you could walk straight into BRO. Now the sign-in is the front door, which is why Step 3 above exists.
Neither change makes registration harder once you know about them. They just make the five-minute version impossible if you show up unprepared, which is a very CRA way to run a Tuesday.
One Business Number, Many Businesses
Here is the question that gets answered wrong more than any other on this topic: can you use the same business number for more than one business?
For a sole proprietor, the answer is yes, and it is not optional. The BN attaches to you as a person. If you run a consulting practice and a side venture as the same legal person, both operate under the same BN. If you close one business and start another years later, the CRA issues you the same BN again. You do not get a fresh one.
What you can separate is the program accounts. If you genuinely need each operation's sales tax kept apart, you can request additional GST/HST accounts on the same BN, which is exactly what those `RT0002` and `RT0003` reference numbers are for. Most sole proprietors never need this and are better off with one RT account.
For corporations, it works differently. Each incorporated company is its own legal entity, so each one gets its own BN. Two corporations means two business numbers, always.
The practical takeaway: if you are a sole proprietor wondering whether to register a second BN for a second business, the answer is almost certainly no. If you are thinking about incorporating, that is the point at which a new business number enters the picture.
What to Do After You Get Your BN
Getting the number takes minutes. Keeping the accounts behind it clean is the ongoing job, and it is where most of the year-end pain actually comes from.
Record your full account numbers somewhere findable. All 15 characters, not just the BN. You will need the RT number on every invoice where you charge sales tax.
Put your GST/HST number on your invoices from day one. Retrofitting it onto months of already-sent invoices is genuinely unpleasant, and clients notice.
Track the sales tax you collect separately from your revenue. The GST/HST portion was never your money. Treating it as income is how a filing deadline turns into a cash flow problem. A sales tax calculator helps for one-off checks, but for ongoing tracking you want it happening automatically.
Know your filing frequency before the first deadline. Annual, quarterly, or monthly is assigned when you register, and it determines your filing and payment dates.
This is the part ReInvestWealth was built for. Connect your bank and the AI Bookkeeper categorizes transactions and works out the sales tax treatment as they come in. The numbers behind your RT account stay current instead of being reconstructed in a panic. Receipts go into the Smart Shoebox by upload or email forwarding, then get matched to the transaction they belong to, which is what turns a pile of expenses into an audit-ready trail. When the filing is due, you can file your GST, HST, and QST returns directly from the app.
Frequently Asked Questions
What is an RT number in Canada?
An RT number is your GST/HST program account with the CRA. It is not separate from your business number: it is your 9-digit BN, followed by the letters RT, followed by a 4-digit reference (usually 0001). A complete RT number looks like `123456789 RT 0001` and should appear on invoices where you charge sales tax.
Do I need a business number if I am a sole proprietor?
Only if you need a CRA program account. If you collect GST/HST, have employees, or import and export, yes. If you are under the $30,000 small supplier threshold, have no employees, and operate under your own legal name, you can wait. Many sole proprietors register voluntarily anyway so they can claim input tax credits on business purchases.
Can I use the same business number for two businesses?
If you are a sole proprietor, yes. Your BN belongs to you as a person, so every unincorporated business you run uses the same one, and you can add separate GST/HST reference numbers if the operations need to be kept apart. If each business is separately incorporated, each corporation gets its own BN.
Can I still register for a business number by phone?
No. The CRA stopped accepting phone registrations for business numbers and program accounts on November 3, 2025. Registration is done through Business Registration Online, which since July 14, 2026 requires you to sign in with a CRA account, a Sign-In Partner, or a BC or Alberta provincial partner login.
How much does a business number cost?
Nothing. Registering for a BN and for CRA program accounts is free, whether you do it online or by mail. Anyone charging you a fee is charging for the convenience of filling in the form, not for the number itself.
How long does it take to get a business number?
Through Business Registration Online, you get the BN and any program accounts immediately in the same session. By mail using Form RC1, expect several weeks.
Your business number is the easy part. Keeping the accounts behind it accurate all year is what saves you at filing time. Connect your bank, let the AI categorize as you go, and see where you stand without waiting for year-end. See plans and what is included.
A note from our CPAs: This guide is educational and covers the general rules for Canadian small businesses. Tax situations vary, so for advice on your specific circumstances, talk to your accountant. (If they use ReInvestWealth, they will already have clean books to work from.)
Written by Maryam Ajorloo, CPA
Maryam Ajorloo is the co-founder of ReInvestWealth and a CPA who specializes in small business tax, sales tax, and everyday bookkeeping. She helps entrepreneurs keep clean, audit-ready books and make sense of write-offs, filing deadlines, and the numbers behind their business. Read more · Connect on LinkedIn
Reviewed by Behdad Karimi Dermeni, CPA
Co-founder of ReInvestWealth and a founding community builder at Stripe. Behdad built ReInvestWealth to give smart, busy entrepreneurs CPA-level accounting without the CPA-level price tag. Read more · Connect on LinkedIn
