talk to your employer because income taxes are usually withheld when RSU's are sold
There will be no federal penalties for not paying in enough taxes during the year if withholding
1) and timely estimated tax payments equal or exceed 90% of your 2021 tax
or
2) and timely estimated tax payments equal or exceed 100% of your 2020 tax (110% if your 2020 adjusted gross income was more than $150K)
or
3) the balance due for 2021 after subtracting taxes withheld is less than $1,000
or
4) your total taxes for 2021 are less than $1,000
generally, tax professionals would use option 2 for their clients because the number is known before the end of 2021. this could include generating estimated tax payments if it looks like withholding won't be enough.
The annualized installment method works best for those who realize most of their income after the 5th month. The AI method requires every line item on the return to be determined for the first 3 months, then 5 months then 8 months and the whole year which is the same as what's on the return.
