Agree with @dmertz . Whatever amount you determine you need to pay should be withheld by the plan using their normal procedure for tax withholding. (Same with state income taxes.) If you take the entire amount in cash, and then make an estimated payment to the IRS later, you could be subject to a penalty for underpaying your taxes unless you file a special extra form with your tax return.
(If you do decide to take the entire amount and pay later, the deadline for paying estimated taxes on income paid between September 1 and December 31 is January 15, 2025.)
