If box 7 has code 4 and no other code, this is not a distribution from any kind of Roth account. If the IRA/SEP/SIMPLE box is marked, the distribution is from a traditional IRA and is generally fully taxable. If the IRA/SEP/SIMPLE box is not marked, the code-4 distribution is from a traditional account in an employer plan and is taxable to the extent shown in box 2a.
The Form 1099-R is required to be entered as received. Whatever amount is shown in box 4 will be credited on your tax return against your overall tax liability determined on your tax return. The amount withheld for taxes on this distribution, usually 10%, is probably insufficient to cover the increase in your tax liability resulting from this distribution, so entering this Form 1099-R is likely to decrease your refund or increase your balance due.
