Sometimes I do very short term work as a contractor (like one or two days). Sometimes companies insist I use their template for filling out my invoice. Some insist they need my SIN (SIN is Canada's version of SSN) but this is wrong because I'm a contractor and they're not taking off tax.

When I tell them this it just falls on deaf ears and they say "we need it".

In these types of situations where the company is insisting they need some personal information and it's not worth hiring a lawyer to fight, is there anything that can be done? In another example a company wouldn't pay me until I filled out a tax form that wasn't even the right one.

Update: I asked and they said the SIN is so they can issue a T4A. I'm not sure if this makes sense.

  • 2
    Shouldn't payment terms be sorted in the contract you signed/agreed to verbally, with all the details exchanged before any work start? Why can't that be the solution?
    – Aida Paul
    Apr 22, 2023 at 20:13
  • Are you incorporated, or operating as a sole proprietor? Apr 22, 2023 at 21:22
  • @joeqwerty It doesn't work like that in Canada. Companies don't deduct tax from payments to contractors. The contractor sorts it out for themselves with the government. Apr 23, 2023 at 3:36
  • @DJClayworth How would Canada government know how much the OP's client pays the OP? How does the government do the audit when the OP pay taxes?
    – Nobody
    Apr 25, 2023 at 9:59
  • Removed some comments about the USA processes, they're not relevant to a question about Canada and may confuse some people
    – Kilisi
    Apr 25, 2023 at 12:13

2 Answers 2


This is tricky stuff, and you may have to give. But there are some things you can do.

First, to settle any doubt, you are absolutely correct. A company does not need to know your SIN if they are not deducting personal tax, and they should not be deducting personal tax from payments to a contractor. It is illegal in Canada to deny someone service because they choose not to provide their SIN, and the government does take seriously the issue of people asking for SINs when they don't have to.

Start by quoting the government statements on the matter. That page is a good place to start, and it also gives some advice on what to do if you are asked for your SIN inappropriately. Send them the page and follow the advice. In particular follow the advice which says to ask detailed questions about what the SIN will be used for.

I'd lay pretty good odds that you are dealing with a junior staffer who has just been told "ask for their SIN" and hasn't been given any other information. If they can't tell you what it's going to be used for that would make the odds even greater - and you can tell them that if they don't know what it will be used for then you don't need to give it to them.

Probably your best bet is to talk to someone more senior, or make them talk to someone more senior. Someone in the legal department instead of finance or HR would be better.

I would personally take quite a stand on this, but in the end if they absolutely refuse to listen to reason or legality it may be simpler to just give them what they want.

If they aren't going to use the SIN, then you might consider giving them a fake SIN, since it won't make any difference. You can always claim it was a mistake if they ever find out - they aren't going to bring legal action if they weren't legally allowed to collect it in the first place. I did that once to a company who demanded my SIN, but swore that it was "only to distinguish duplicate records in the database". I have a very unusual name and the chances of having someone on their payroll with the same name is zero.

EDIT: All of the above assumes you are doing work through some kind of small company, like a "sole proprietorship". This is normally how things are done. If you are contracting as a private individual, without any kind of company, then they may need your SIN because they have to treat you like an employee.

  • 1
    @Hilmar we just don't have private companies lobbying against a simplified tax system. I didn't file my taxes for 10 years and then did it in one go. Got 10 years of tax refund.
    – Nelson
    Apr 24, 2023 at 1:45
  • They said it's because they issue a T4A. Does that make sense? Is issuing a T4A a valid reason to need the SIN?
    – GlaceBuff1
    Apr 25, 2023 at 8:10
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    From canada.ca/en/revenue-agency/services/tax/businesses/topics/… "If you do not have the SIN, enter nine zeros" -- they do not need it. My incorporated firm provides services to Canadian firms (we invoice) and NEVER have any of us received a T4A. So another answer is "don't do T4As then" but if they want to, they still don't need your SIN. Apr 25, 2023 at 11:59
  • 1
    @GlaceBuff1 Please edit that info into the question. Do you have a company for the consulting? A sole proprietorship? Apr 25, 2023 at 13:22
  • 5
    Then that's probably the explanation. If you don't have a company they probably have to treat you like an employee, which may mean they have to deduct tax which means they need your SIN. Possibly. I'm unclear as to the exact legal details. Creating a sole proprietorship is cheap and easy and would solve some of these problems. Apr 25, 2023 at 20:28

In these types of situations where the company is insisting they need some personal information and it's not worth hiring a lawyer to fight, is there anything that can be done?

You can decline the gig.

As a contractor, any time a company wants something from you that you don't want to give, and you don't want to fight it legally, you can just deny your services and walk away.

You always get to decide what you are willing to do, and what you will not. Some are asked to modify their CV/resume. Some are asked to do work they find repellant. Some are asked to provide unneeded information or fill out useless forms.

In all cases, as a contractor, you get to pick and choose. You get to decide the line beyond which you will not step. You are in control.

  • 1
    I declined a contract when the person insisted that I sign the termination agreement before I had even started.
    – David R
    Apr 23, 2023 at 14:29
  • 1
    I don't think it is wise to skip on a lucrative business opportunities just because of a trivial bureaucratic disagreement like this. The answer by DJClayworth, which recommends to first try to explain to them that they don't need that information, is a far more reasonable approach.
    – Philipp
    Apr 26, 2023 at 15:19

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