Thanks for the response,

Do you know what others are doing to show tax included amounts. I can see that we can show the extension is tax in, but I can't think of how to make the invoice sensible if the unit price is tax out. I suppose your column heading could show the unit price as a tax out price and the extension as tax included. What do you think?

I don't believe there is a way of doing a calculated field in the spec?

Mike