I need help understanding why the withdrawal from 401k for down payment on house impacts the covid check?

[CatinaT1]

Why do you think it will have any effect?

Watch this website for the latest updates https://www.irs.gov/coronavirus

[dmertz]

A withdrawal from a 401(k) generally raises AGI and above a certain AGI further increases in AGI decrease the amount of the tax rebate you will be are eligible to receive.

If you haven't yet filed your 2019 tax return and your 2018 AGI is less than what your 2019 AGI will be, you might wan to delay filing your 2019 tax return so that the rebate will be based on your 2018 AGI instead of your 2019 AGI.