### Title

How to exclude a particular item type from a calculation.

### Post

In my invoicing system, I have an invoice layout with a line item portal. There is a "subtotal" field which uses the calculation: "Sum ( Line Items::RetailPrice )". Their is a "sales tax" field which uses the calculation: "Subtotal * .07".

We have some line items which should not be charged tax. Example: Security Deposits.

Is there a way to make the "sales tax" calculation not include certain items? Something like "(Subtotal *.07 unless subtotal includes "security deposit" and or "labor", in that case, subtact total of all security deposits and labor from subtotal, then multiply by .07)

How would I script this in the "Specify Calculation" dialouge box? Is there an easier approach?

That's essentially what I have already suggested. The only change is quite trivial:

f ( Taxable = "yes" ; RetailPrice )