I'm looking for an alternative to the IF function detailed below based on 12
nested formulas ie January - December so that depending on which month is
specified in the "input date B1" the year to date column returns the sum of a
differing number of columns....

If the input date is month 1 then the calculation returns the value in
column Q24
If the input date is month 2 then the calculation returns the value in
column P24:Q24
If the input date is month 3 then the calculation returns the value in
column O24:Q24 and so on....

Any ideas?

=IF('Input Date'!$B$1=1,SUM(Q24),IF('Input
Date'!$B$1=2,SUM(P24:Q24),IF('Input Date'!$B$1=3,SUM(O24:Q24),IF('Input
Date'!$B$1=4,SUM(N24:Q24),IF('Input Date'!$B$1=5,SUM(M24:Q24),IF('Input
Date'!$B$1=6,SUM(L24:Q24),IF('Input Date'!$B$1=7,SUM(K24:Q24),0)))))))