1099-R Box 7 Code D4

Hello, 

In 2020 I received an inheritance from my grandfather and received a 1099-R.  Here is what is listed on my 1099-R

Box 1: $37,894.00 (gross amount)
Box 2a: $531.46 (taxable amount)

Box 2b: Taxable amount not determined: unchecked
Box 5: $37,362.55 (employee contribution/designated roth contributions or insurance premiums

Box 7: D4

Total Distribution box: checked

Now, I know I will pay tax on the $531.46 beacause its taxable income.  The amount in box 5 that has $37,362.55 that portion of the distribution is not taxable income to me correct?