@balebako - what are you and your spouse agreeing to? that $1100 was a joint asset and both of you 'own' it.  if you report the entire $1100 as your payment and yours only, what is your spouse's lawyer going to say??????? 

The IRS Instructions for Form 1040, page 37, say the following.

"If you and your spouse paid joint estimated tax but are now filing separate income tax returns, you can divide the amount paid in any way you choose as long as you both agree. If you can't agree, you must divide the payments in proportion to each spouse's individual tax as shown on your separate returns for 2021. For more information, see Pub. 505. Be sure to show both SSNs in the space provided on the separate returns."

50/50 if you're in a Community Property State.