Enter your portion of the stimulus you received which is half. Do not enter the total amount received for both of you.

Stimulus payments were advances on the Recovery Rebate Credit.

If you received the full amount of both stimulus payments (Economic Impact Payments), you won’t get any additional credit on your return this year since you’ve already received the full amount of the credit as stimulus payments.

If you didn't receive the full amount for your first or second-round stimulus payments, we'll help you claim the Recovery Rebate Credit when you file your taxes this year.

Here’s how:

• When you’re ready to file, we’ll check if you meet eligibility requirements for the stimulus payment. If you meet the requirements, we'll ask a few questions about any payments you've already received and then let you know if the Recovery Rebate Credit applies.
  • If you need to make any changes to your stimulus credit responses, search for stimulus and select the jump-to link at the top of the search results to return back to the section. Enter your updated info and Continue.

It’s important that you enter the correct amount of each stimulus payment you received. The first stimulus payments were made between April and September of last year, while the second round of payments were delivered during January and February. You can find the exact amount,

• On your IRS letter-Notice 1444 and/or 1444-B which were mailed to you with the headline, “Your Economic Impact Payment Has Arrived” and were signed by the president. Or,
• By visiting IRS.Gov and creating or accessing your account. Or,
• In your bank statements. You might be able to search your online statements for deposits made by the IRS or US Treasury.

Additional information: Eligibility rules for the Recovery Rebate Credit

I have a similar situation: My wife and I divorced around the same time the first stimulus payment was sent. The payment was a joint payment so we split the payment. Now divorced we will be filing single returns in 2020. Form 1444 lists a joint payment of $1800. How do we report the stimulus payment we received on our 2020 tax forms?  Line 16 of the The Recovery Rebate Credit Worksheet states the following.  

"Enter the amount, if any, of the economic impact payment (EIP) 1 that was issued
to you (before offset for any past-due child support payment). You may refer to
Notice 1444 or your tax account information at IRS.gov/Account for the amount
to enter here."

You would each report half.