That depends. If your withdrawal falls within the guidelines for the deferral, you will need to complete the form 8915-E but that form is not ready in TurboTax. The form 8915-E will deal with the Cares Act retirement distribution exclusions and has not been released by the IRS. We do not anticipate this form being completed and released until mid-February. After you enter your retirement plan distribution in the 1099R screen then continue, you will see a screen for "Uncommon Situations". The first box relates to natural disasters, including Covis-19. Once that box is active, you will be able to enter your 2020 pandemic retirement distribution information. This form should be released around 2/18.
The advantages of spreading the withdrawal amount over 3 years is you could possibly be taxed at a lower tax rate, depending on your income levels. Also, the 10% withholding you mentioned is just that, withholding much like the federal withholding off your pay check. That probably will not be the amount of tax will end up paying on the distribution, again depending on which tax bracket you are in. But breaking the distribution up and paying taxes on it over 3 years does have some advantages if you are being pushed into a higher bracket by the additional income from the withdrawal.
Here is some information on early withdrawals and the pandemic
