Regarding the CARES act, the IRS has not released the form so we have no idea when you will be able to file.
Regarding the tax, any withholding at the time of withdrawal is only a mandatory minimum. You must report the withdrawal on your tax return. Your tax owed for the year is calculated from all your income, dependents, credits and so on. You get credit for the amount withheld. Then if you owe more, you make an additional payment, and if you owe less than was withheld, you get the difference as a refund.
