What do I put for amount received for the child tax credit and stimulus payment when I received the payments when married but am now divorced?

This is going to be messy ... each of you must enter the amount of the advance CTC that you got on your own return even if you are not claiming the child this year due to divorce ... you each will get a letter 6419 in the mail from the IRS and you must each enter your info on your return.   So if you got 1/2 of the advance reported in your name   and you are claiming the child then you will get the rest of the credit on your return.    The other parent will also have to report the amount they got in advance  HOWEVER since they are not claiming the child they may need to repay all or some of the credit back ... that is just the way the law was written.   If you would like to be nice you can reimburse them for the money they lost but you are not required.  

INFO FOR DIVORCED PARENTS:   

There is no such thing in the Federal tax law as 50/50, split, or joint custody.  The IRS only recognizes physical custody (which parent the child lived with the greater part, but over half, of the tax year.  That parent is the custodial parent; the other parent is the noncustodial parent.)

Who can claim the exemption and credits depends on who is the custodial parent. (By the IRS definition of custodial parent for tax purposes - this is not the same as the custody that a court might grant.).

The test that the IRS uses to determine the custodial parent is where the child lived for more than 1/2 (or greater part) of the year. The IRS will go so far as to require counting the nights spend in each household - that person is the custodial parent for tax purposes (if exactly equal and more than 183 days - The custodial parent is the parent with the highest AGI, if less than 183 days then neither parent has custody). That can usually only occur if both parents lived with the child at the same time.   And yes they are that picky.

The custodial parent may claim everything child related  UNLESS they waive the dependency exemption to the non custodial parent via a form 8332.... in that case the child may be used on 2 separate returns but only in the following way :

Only the Custodial parent can claim: (Child would be listed as non-dependent EIC & CC only)
-Head of Household 
-Earned Income Credit
-Child Care Credit

The non custodial parent can only claim: (Child would be listed as dependent)
-The Exemption
- The Child Tax Credit

See Special rule to divorced or separated parents (or parents who live apart) on page 32:
https://www.irs.gov/pub/irs-pdf/p17.pdf

But only if specifically specified in a pre-2009 divorce decree, separation agreement or the custodial spouse releases the exemption with a signed 8332 form - after 2009 the IRS only accepts a signed 8332 form that must be attached to the non-custodial parents tax return.