Are you supposed to attach a copy of your W-4 somewhere, if so where?

[tagteam]

Did you mean to write "W-2"?

You give the W-4 to your employer.

[xmasbaby0]

A W-4 is the document you give to your employer to tell them how much tax to withhold from your paychecks.   It only goes to your employer---nowhere else.    When you prepare your tax return, you enter information from the W-2 that your employer gives to you at the beginning of the tax season---usually by the end of January.   If you e-file, you do not have to mail anything.   If you file your return by mail, you have to attach a copy of your W-2 to the Form 1040 that you send in to the IRS.

This is what a W-4 looks like:

https://www.irs.gov/pub/irs-pdf/fw4.pdf

This explains a W-2:

https://turbotax.intuit.com/tax-tips/irs-tax-forms/what-is-a-w-2-form/L6VJbqWl5