I'm assuming you have an "Item Description" column on your invoice form. If
so then what you could do is precede your Heating control item with the
letters "HC-", then use the formula below in the tax amount column:
=IF(LEFT(C1,2)="HC",D1*5%,D1*17.5%)

Also I would set up 2 cells to represent your tax rates, name each cell
....say tax1 and tax2 and use that in your formula, that way if the tax rates
changes down the road you would only have to update those 2 cells. So the
formula would look like:
=IF(LEFT(C1,2)="HC",D1*tax2,D1*tax1)

Note. to name a cell, select it and hit CTRL+F3 and type the name in the
first box, hit OK.

Hope it's something you can use!
JG

"PJOS11" wrote:

I`m a Heating engineer and carry out high efficency heating systems so not
every job is the same price. The heating controls are charge at 5% and the
rest of the work at 17.5%. So the amounts will change every job
Is it possible to do this on exel sales invoices?

" wrote:

"PJOS11" wrote:
If I am invoicing say £1000. Seven hundred of this
maybe charged at 17.5% and the remaining £300
would be charged at 5%.
[....]
£700+17.5%=£822.50
£300+5%= £315.00
Total £1137.50

If the tax rule is as simple as the above, the following
should suffice (assume the invoice amount is in A1):

=A1 + 17.5%*MIN(700,A1) + 5%*MAX(0,A1-700)

However, responses from others lead me to suspect
that your description of the tax rule is misleadingly
over-simplified. GIGO.