@DoctorWho Yes you figured it out. The 8400 in April 2021 was for the 3rd Stimulus payment. You don't enter the 1st or 2nd rounds on your 2021 return.
The first 2 Stimulus checks were for 2020. The first one was 1200 (2400 married) and 600 for each dependent under 17. The 2nd one was 600 per person and dependent under 17. It came out in Dec 2020 - Feb 2021 but went on your 2020 tax return.
The latest 3rd stimulus came out starting in March 2021 and is 1400 per person no age limit. The IRS also sent out letter 6475 telling you how much they sent you. They send letter 6475 to each spouse for half. But you need to enter the total .
