I had a child in 2018 so for the year I put she was with me for 12 months. For 2019 I also put that even though I split 50/50 custody with her father and he is claiming her on his taxes. They got den

[ReginaM]

Both you and the father of your child can not claim your daughter.  Only one of you can claim her.  

In most cases, because of the residency test, a child of divorced or separated parents is the qualifying child of the custodial parent.  For IRS purposes there is no such thing as a 50/50 child.  You will need to count the nights that your child spent with each of you to determine who can claim her on their return.  

However, the child will be treated as the qualifying child of the noncustodial parent if the rule for children of divorced or separated parents apply.  

See IRS Publication 504 for more details on who should claim your child.

[christinebyers]

I mistakenly clicked through having her for 12 months on my 2019 taxes when in reality he had her more and is able to claim her. I made the mistake. Should I amend my tax return to 5 months and his to 7 in order to reflect that? Or is there another way to fix this?

[CatinaT1]

There is no way to reset the e-File system for this tax year, so her father will have to mail his tax return in this year.  

His tax return will be properly processed with her as a dependent; it just cannot be e-Filed.

If your return mistakenly shows her as a dependent, you will need to amend your return.  To amend your return, wait until you receive your refund, log back into TurboTax, and select the option "I need to amend my 2019 tax return."   Your amended return will need to be mailed in for processing and may require the return of some of the refund.  

You can find more detailed instructions on that process here: How to amend a tax return in TurboTax.