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Tax identification in Canada means one of a few nine-digit numbers, and which one you use depends on who you are. Most people use a Social Insurance Number (SIN), issued by Service Canada. Non-residents who can’t get a SIN apply to the CRA for an individual tax number (ITN), and a business gets a business number (BN).
Which number do you actually need?
Start with what you’re doing. Working a job, filing a return or receiving a T4 slip all mean a SIN, and most readers can stop right there. Living abroad and owing Canadian tax means an ITN if you aren’t eligible for a SIN. Running a business with a GST/HST or payroll account means a BN.
| Number | Who it’s for | Who issues it |
|---|---|---|
| SIN | Individuals who work or file in Canada | Service Canada |
| ITN | Non-residents not eligible for a SIN | The CRA (form T1261) |
| Temporary tax number | Filers without a SIN in time for the deadline | The CRA |
| Business number | Businesses and incorporated entities | The CRA |
Canada has no single card called a tax identification number. That’s the phrase forms from other countries use, and it’s where the confusion starts. If a foreign form asks for one, read its instructions to see what to enter. We couldn’t confirm a rule that fits every form.
When do you have to hand over your SIN?
To anyone who prepares a T3, T4 or T5 slip for you, such as an employer, a bank or a trustee. And to the CRA when it asks. The CRA page says that failing to provide it when required can cost you a $100 penalty. Beyond those cases, ask why before you share it. Service Canada is blunt about the stakes.
Your SIN is private and it is illegal for anyone else to use it.
Social Insurance Number, canada.ca
Each year, look at your slips. If a SIN is missing or wrong on one, tell whoever prepared the slip. The CRA says to do exactly that. A typo on a T4 can leave an employer’s report and your return not matching, and that’s a headache you can avoid with a two-minute email in February.
How does a non-resident get an individual tax number?
You fill in form T1261, add certified copies of ID (a passport works), and mail the lot to the Sudbury Tax Centre. The CRA says to allow six to eight weeks, so start early if you have a filing deadline coming up and no number yet. International students without a work permit are a typical case. With a work permit, you need a SIN instead.
An ITN is used to file returns, report the sale of taxable Canadian property, ask for a lower withholding tax and file Underused Housing Tax returns.
What is a business number, and when does a sole proprietor need one?
A BN is nine digits. The CRA adds letters and four more digits for each program you register, so a GST/HST account reads RT, payroll reads RP, corporate income tax reads RC and information returns read RZ. You can only have one BN per business, and new accounts get added to it.
An unincorporated business needs a BN only once it registers for one of those accounts. That means a freelancer can file taxes for years on a SIN alone. Incorporating changes that straight away.
What does that look like with real numbers?
Take a freelancer in Ontario with $40,000 of net self-employment income. She files under her SIN, and the income tax calculator shows $4,221 of income tax. The self-employed tax calculator adds CPP contributions of about $4,344, and she keeps roughly $31,435. No BN needed yet.
Now say she registers a GST/HST account. She gets a BN with an RT ending, and it goes on her sales invoices and returns. Her personal filing still uses the SIN. The two numbers live side by side, like a house key and a car key: different locks, same person.
If she pays instalments, the instalments calculator can size them. The payroll deductions calculator matters if she hires help, because that means an RP account.
What if you’re waiting on a number and tax time is close?
Don’t sit on the return. The table above lists a temporary tax number for exactly this spot, and an ITN covers non-residents. Mention the situation when you contact the CRA, keep a copy of whatever you sent, and file by the deadline rather than after the number turns up. A late return costs more than a few awkward weeks of paperwork.
What mistakes cost people time?
Using a friend’s or a former employer’s numbers on a form. Guessing a business number instead of looking it up. Sending an ITN application without the certified copies the CRA asks for. And filing late because a SIN hadn’t arrived, when a temporary tax number or ITN would have let you file on time.
Another quiet one: mixing up which number goes where. An invoice carries the BN, a T4 carries the SIN, and sending the wrong one to a client or the CRA just means a phone call you didn’t need.
The calculator above is an estimate. It leaves out EI for the self-employed and treats her as having no other income.
Where does this information come from?
The SIN, temporary tax number and ITN details come from the Canada Revenue Agency‘s pages on the SIN and on applying for an ITN. The business number facts come from the CRA’s business registration pages. Dollar figures use 2026 rules. This site is independent and has no link to the CRA or Service Canada.
Frequently asked questions
Does Canada have a tax identification number?
There's no single one by that name. Individuals use a SIN, some non-residents use an ITN, and businesses use a nine-digit business number.
Who issues a SIN?
Service Canada. It is a nine-digit number used for income tax and some federal programs.
What if I don't have a SIN by the filing deadline?
The CRA says to file with a temporary tax number or an ITN, whichever applies. If neither fits, file a paper return with a cover letter and certified proof of identity.
How long does an ITN take?
The CRA says to allow six to eight weeks after it receives form T1261 and your documents.
Does a sole proprietor need a business number?
Only once the business registers for a CRA program account such as GST/HST or payroll.
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