Thanks Rylo

But this has still not worked!

This still does not erdicate the value in col M when value in col K is NOT the highest for that therapist in that week.

Using the above formula you suggested and placing it in M3, then selecting it and using the corner handle to copy it down col M - I still get Row 17 showing that Aimee made £714.10 on 08/06/07 (week 2 of yr 07/08 Q1) and there is a value in M17 as 714.10 is above 600 - but this should be "zero", as this is not the MAX value that Aimee has earned in week 2 of Yr 07/09 Q1 - in fact her Max value was earned on Row 20 (09/06/07) - that also has a value in M20.

The pivot table adds the values of M17 and M20 to give 24.98 - when infact her total commission for the week is value in M20 only i.e. 13.57.

still needs more teaking - the formula:

M17: =IF(K17>L17,(K17-L17)*0.1-SUMPRODUCT(--($B$2:B16=B17),--($G$2:G16=G17),($M$2:M16)),0)
M20: =IF(K20>L20,(K20-L20)*0.1-SUMPRODUCT(--($B$2:B19=B20),--($G$2:G19=G20),($M$2:M19)),0)

Are these correct?