How do I automatically calculate YTD numbers by changing a date?

Do you know a formula to automatically calculate YTD information off of a
date or month? (i.e. I don't want to have to change the formula every month,
I just want to change the month at the top of the spreadsheet and have the
numbers automatically calculate)
I know I can nest a bunch of 'If' statements, but is there an easier way?
Thanks.

How about a brief description of your data: columns, contents/data types, etc

Ron