You must mark the box labeled "I inherited this IRA" because you inherited the IRA from which the distribution being reported on the code-4 Form 1099-R was made. The taxable amount (likely the entire amount in box 1) will be added to your AGI and the tax withholding shown in box 4 of this Form 1099-R will be credited on Form 1040 line 25b. Any state tax withholding shown will be credited on your state tax return.
