You are giving us a lot of information that is unnecessary here to determine if you could claim the children. And you have not mentioned if you are both the bio-parents of the children---that is important. First we can get 2019 out of the way, since it is too late to file a 2019 return and receive a refund. Even if you could qualify for a 2019 refund, it has been forfeited because it is too late.
As for tax year 2020, if all of you were living together, then only one of you could claim the children as dependents on a tax return. If you could not agree at the time, the IRS has some tie breaker rules that could help:
TIE BREAKER RULES
https://itap1.for.irs.gov/owda/0/resource/Commentary_Files_Redirect_ITA/en-US/help/tbrk09.html
You do not say if you filed a tax return for 2020. If you did not file, you have until tomorrow--Friday, May 17, 2024 to file a 2020 tax return and still get a refund--or it will be too late and the refund will be forfeited--meaning the IRS will not pay it. If you did file a 2020 return, then you can try amending it to claim the children and then wait for the IRS to sort out which one of you could claim them. (That will take months).
If you need to file an original 2020 return:
You cannot change the tax year. The current online program is for 2023 only. Only a 2023 return can be prepared online and only a 2023 return can be e-filed.
Online preparation and e-filing for 2020, 2021, and 2022 is permanently closed.
To file a return for a prior tax year
If you need to prepare a return for 2020, 2021, or 2022 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.
https://ttlc.intuit.com/community/state-taxes/help/how-do-i-contact-my-state-department-of-revenue/0...
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.
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.
If you need to amend your 2020 return:
See this TurboTax support FAQ for amending a tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...
Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.
You can watch for information here:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
**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.**
