A work permit issued by Canada has some numbers that are not labelled explicitly.

  • an 11-digit number (like BB123 456 789) in red ink at the top right, in a rounded box
  • a 10 digit number (like U123456789) in black ink below the rounded box

There are also these labelled numbers:

  • OFF. FILE NO (like W123456789)
  • CLIENT ID. (like 1234 - 5678)

Which of these numbers is the Work Permit number? And what are the other unlabelled numbers called?

enter image description here

  • Do you have an update on this? What number did you end up using?
    – Dipen Shah
    Mar 22, 2017 at 12:22
  • No update. I used the one in black ink.
    – Liam
    Mar 30, 2017 at 19:40
  • If a number has 9 numerical digits, and the first digit is "9", it's likely your temporary Social Insurance Number. Nov 18, 2019 at 14:21
  • Use the number in black ink that starts with 1 letter and then has 9 digits
    – Valentino
    Jun 30, 2023 at 18:50

1 Answer 1


It's the one that says UCI or Unique Client Identifier which according to your question is the Client ID. This is the number that is used everywhere (may it be for extending the work permit or applying for permanent residence).

This number remains the same for your period of stay in Canada. If is of the format:

four numbers, a hyphen and four more numbers (Example: 0000-0000) or

two numbers, a hyphen, four numbers, a hyphen and four more numbers (Example: 00-0000-0000)

You can find more info about UCI here and here.

I am guessing the other numbers are used by CIC internally and I have never needed these numbers for anything in that matter.

Also, this was the message written on one of the letter I received from CIC which was regarding my work permit.

enter image description here

If something provides personal information to my file, it should be the number that CIC would ask in this case.

  • 2
    I doubt this, because on some forms such as IMM5708E they ask for both UCI and a 'Document Number' - "If applicable, provide the document number of the most recent Visitor Record, Study Permit, Work Permit or Temporary Resident Permit issued to you"
    – Liam
    Mar 7, 2017 at 19:43
  • @Liam UCI is not always known as mentioned here if you're applying for the first time. As you said most recent Visitor Record, Study Permit, Work Permit or Temporary Resident Permit it could mean any type of document, not just work permits. In case of work permits, it is always the UCI. You could have a study permit but be applying for a work permit. In that case, the UCI would be the one mentioned on your study permit.
    – Dipen Shah
    Mar 7, 2017 at 19:55
  • @Liam UCI is not a compulsory field if you noticed in the form you linked.
    – Dipen Shah
    Mar 7, 2017 at 20:00

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