If approximate is close enough then do this

A1: earning for this month
B1: tax allowance (e.g. 4895)
C1: 10%
B2: 2090
C2: 22%
B3: 32400
C3: 40%
A2: =MAX(($A$1-SUM($B$1:B1)/12),0)*C1
A3: =MAX($A$1-B1/12-B2/12,0)*(C2-C1)
A4: =MAX($A$1-B1/12-B2/12,0)*(C2-C1)

and the answer in A5

=ROUND($A$1-SUM(A2:A4),2)

--
HTH

Bob Phillips

(remove nothere from email address if mailing direct)

"DarkNight" wrote in message
...
thanks guys for taking the time to respond to this post.
think i'm getting somewhere...
when i calculate my gross earnings for a week i then divide by a % this
however changes with diffrent amounts of pay.. but would like it to auto
calculate.
p.s. it dosent have to be 100% right just a rough estamate would be nice.
i've even been to the inland revenue site and there calculator gets me
somewhere near old payslips.