You will be taxed at your marginal tax rate and can pay it in one lump sum using form 1040-ES. 

https://www.irs.gov/pub/irs-pdf/f1040es.pdf

Yes you can send in a one time estimate.

Here are the blank Estimates and instructions…..

http://www.irs.gov/pub/irs-pdf/f1040es.pdf

Or You can pay directly on the IRS website https://www.irs.gov/payments

Be sure to pick the right kind of payment and year.....2021 Estimate

The payment is just an estimate.  You will still need to enter the gross amount into your tax return next year and it will increase your income so the tax may be more.  Then you will get credit for the estimated payment.  

Oh and don't forget your state tax too.

Thank you very much. That is what I needed to know.

Wonderful and the extra info about the "only an estimate" is great info. Thank you

Thank you for that also. Is there another form for state or does the rollover count against me with for extra income?

Yes the rollover is added to your income and taxable.  You need to go to your state's website to pay an estimate or get the state blank forms.  Which state?

For the great state of Michigan

You do know you can google search things for yourself in 10 seconds or less ...

https://www.michigan.gov/documents/taxes/2021_MI-1040ES_714366_7.pdf

Thank you critter google. Every article I read only said you had to pay your taxes. It gave zero information on the process and that is why I asked a community that is here to assist.