This is not something to bury your head in the sand about. You do not say how long it has been since you filed a tax return. Any tax refunds for years earlier than 2017 have now been forfeited, but if you owe, the IRS wants to be paid no matter how many years it has been. Not filing your tax returns can cause problems for you not only with the IRS but ---down the road---with Social Security. If you ignore the problem you could end up in a situation in which you are unable to collect your Social Security benefits or get Medicare someday.
If you have been a W-2 employee, then get busy and ask the old employers for copies of your W-2's. Call them, email them, snail mail them and/or stop in personally to ask for copies of your W-2's. If you were an independent contractor then 1099Misc forms may have been sent to the IRS by the businesses or individuals who you worked for. Or you may need to to enter cash payments you received without documentation.
What if I do not file my tax return?
https://ttlc.intuit.com/questions/2572308-what-happens-if-i-don-t-file-my-taxes
It is possible to get a wage and income transcript from the IRS that will show the amounts paid and withheld reported by employers, etc. but that will show only the federal amounts. The state information will not be on the transcript--and you may need to deal with your state too if you live in a state that has a state income tax.
https://www.irs.gov/individuals/get-transcript
Social Security has copies of W-2's but it is expensive----$86 per copy to get a copy of a W-2 from them.
https://www.irs.gov/help-resources/tools-faqs/faqs-for-individuals/frequently-asked-tax-questions-an...
If it has been a very long time since you filed a tax return and you expect to owe a lot, you should seek paid professional tax help. A tax professional may be able to negotiate with the IRS if you owe a lot.
If you want to tackle the tax returns yourself, you can get software for tax years 2017, 2018 and 2019. Software for earlier years is no longer available. But you can get the paper forms from the IRS to prepare by hand
Each tax year has to be prepared and filed separately using the forms for the specific tax year. They cannot be combined in any way--do not even put them in the same envelope when you mail them.
Online preparation and e-filing for 2017, 2018 and 2019 is permanently closed.
To file a return for a prior tax year
If you need to prepare a return for 2017, 2018, or 2019 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
https://turbotax.intuit.com/personal-taxes/past-years-products/
You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.
Remember to prepare your state return as well—if you live in a state that has a state income tax.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.
Federal and state returns must be in separate envelopes and they are mailed to different addresses. Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.
Note: The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac. It cannot be used on a mobile device.
If you are getting a refund, there is not a penalty for filing past the deadline. If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
