Thanks for link and suggestion.
I'm ok with those particular calcs for discrete periods.
What I wish to do though is to compare versus the same period of the year as last year only up to the proportion of the year observed e.g. on the 15th of January I want to see how much I've done for the Year to date compared to the 1st of Jan to the 15th of January of last year?
Bar: 1st Jan - Today; Year N
Line: 1st Jan - Todays Date, Year N -1
After a few hours of searching I've managed to find a solution.
For those who may follow up on this or read the thread I found it via the following field:
Return the true, and you'll always have only through day #(today's day of year number)
Using DATEPART will work across all years.
%$%@$;) where did you find that? GREAT:)
It was hidden away on page 2 of this link (post by Colby):
I tried a few of the other suggestions in there, nearly missed that one, but it's easily the best solution to it. Funnily enough it seemed to go largely unnoticed within that thread also.