I have created a spreadsheet which details a number of invoices for one
client, and gives a nett total invoiced. As part of the contract we are
required to give 1% discount on all sales between 150K and 300K and 2% on any
sales above 300K.

I have entered the percentages and the discount limits of 150 and 300 in
separate cells for ease in the event these may change.

I have solved the 2% discount with the formula:
=IF(D39B44,SUM(D39-B44)*C44) and this works fine. My problem is trying to
get a formula working which calculates 1% of the sales between 150K and 300K.
Can anyone help?

I have listed the cells for assistance.
D39=Nett Sales
B43=150,000 (1% lower limit)
C43=1%
B44=300,000 (2% lower limit)
C44=2%

Thanks in advance
Steve