Yes, that's possible.

In the Data Validation screen, you have a Custom option, where you can enter
a formula. Use it to represent your condition.

--
Wigi
http://www.wimgielis.be = Excel/VBA, soccer and music


"Anita" wrote:

I have set up a custom cell validation that only allows 10% or less of a sum
in a specific cell to be added in the validated cell. I want to set up a
condition that the validation should only apply if a different cell contains
a value. This would be like an "on" switch for the validation. Is this
possible?
--
Anita