How can I claim my money back from incomplete IRS stimulus refund based on larger 2018 income rather than 2019 smaller amount? Didnt get $1200

[MissMCJ]

You will claim it on your 2020 tax return.  TurboTax will ask if you received the stimulus as part of the interview when you do your return.

[NCperson]

at this point, nothing about your 2018/ 2019 information matters with respect to the stimulus.  It's all about what your 2020 status and income are on your 2020 tax return LESS what you may have already received.

At the END of the interview section, there are a number of questions to determine what you are owed and what you have received.  It's not programmed for the 2nd stimulus yet.  What you want to be confident with is what number ends up on Line 30 of Form 1040 - that is the stimulus credit and it will increase your refund.

your 2020 income will determine the stimulus payment you are entitled to - that is the way Congress pass the law related to stimulus.

I wouldn't rush to file until you are confident that the 2nd stimulus is programmed into the software.  We all hope it will be as the submission window doesn't open until late January in any event. 

does that help?