Assume your data goes from row 1 to 30, place this formula in C1 and drag down.
=SUMPRODUCT(--($A$1:$A$30<A1),--($A$1:$A$30>=A1-365),$B$1:$B$30)

Signature
Regards,
Dave
> I am trying to calculate an annualized rolling sum for data as follows:
>
[quoted text clipped - 10 lines]
> I want to be able to calculate on each date the sum of column B for the past
> year.