According to the Internal Revenue Service, you should wait to get your W-2 tax form from your employer before filing your income tax return. But if the form doesn't come and you've reached out to your employer and the IRS, you're still required to file your taxes with your best estimate of what you were paid and what was withheld from your paychecks. One way to do this is by using the information on your last pay stub of the tax year.
TL;DR (Too Long; Didn't Read)
In the event that you did not receive a W-2 form from your employer, you can use your last pay stub of the year to provide the IRS with evidence of your income when you are filing your taxes.
Waiting on the W-2
Early each year, your employer should send you a W-2 tax form showing information such as how much you were paid the previous year and how much was withheld from your paychecks for federal income tax, state income tax, Social Security tax and more.
Your employer should mail this to you by Jan. 31 or make it available to you electronically, such as through an internal human resources website or a payroll provider's online portal. Your employer also should file a copy of the W-2 with the Social Security Administration.
If you haven't received the form, you can contact your employer and ask for it. Sometimes your employer will be able to fax or email you a new one right away or send one to you in the mail.
If you still haven't received it by Feb. 15, the IRS says you should contact that agency to ask for help. The IRS can reach out to your employer on your behalf.
Filing with Your Pay Stub
If even after contacting the IRS you still haven't received your W-2, you can file your taxes without it. You'll need to provide an estimate of the figures that normally would be on your W-2. In many cases, this information, including tax withholding and total pay, will be on your last pay stub of the year. It's a good idea to always save your most recent pay stub, and the last pay stub you've received in any particular tax year.
You can copy the information from your last pay stub onto Form 4852, which is designed to be used along with your main tax return form when you don't receive a W-2 form. If you later find out that the information wasn't quite right, you can file an amended tax return using Form 1040X with your correct income information.
While it might be tempting to file with just your pay stub before trying to get your W-2, especially if you know you're owed a tax refund, the IRS says you should always try to get your W-2 before using Form 4852 to file without it.