Sold rental property. It will close end of Apr 2021. How to compute and pay withholding for federal and CA taxes this year to avoid penalties next year?

[karmic_caboodle]

Property purchased 2002 as primary residence but rented it out past 10 years.

[npierson7]

It depends on two main factors: your gain on sale, don't forget depreciation recapture amount, if any; and your tax bracket. Generally speaking, pay at least 10% of the gain on sale toward federal income tax and 3.5% toward CA income tax.