Yes----that is correct. The checks sent out last year were based on 2018 or 2019 returns so that they could be sent out quickly. But the stimulus checks were really an advance on a 2020 credit. So if you did not receive it last year and you are using the recovery rebate credit----it is based on your 2020 income.
The stimulus check is an advance on a credit you can receive on your 2020 tax return. If something went wrong or you did not get the stimulus check in 2020, you can get it when you file your 2020 return in early 2021
The Recovery Rebate Credit will be found in the FEDERAL REVIEW section. ( you should see "Let's make sure you got the right stimulus amount”) If you are eligible it will end up on line 30 of your 2020 Form 1040.
Make sure that you enter ALL of the stimulus money received for the 1st ad 2ns stimulus for yourself, your spouse and your children.
Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.