Can anyone tell me what formula I can use to calculate the cost before
vat based on the rate here in the UK before and after 1 December?

I know roughly what I want but don't know how to correctly put this
into a formula.

E.g.
I have the date in column J2 e.g. 30/11/2008
The total in column K2 for example £100
In column L2 I will have a formula something like this:
IF date in column J2 = < 01/12/2008 sum K2 / 117.5 * 100 IF date in
column J2 is equal to or than 01/12/2008 sum k2 /115 * 100 else
return error.

So it would give the answer £85.11 with the date as 30/11/2008. If
the date was 01/12/2008 or 02/12/2008 then it would give answer
£86.96.

Thanks for your help with this

John