Ok, I figured out a better way of handling this. Instead of [rate] being a calculated field, I made it a Number with an Auto-Entered value of the rate from the Category database. Thus, by default it shows the true rate, but it can also be modified.

Problem solved!

I'm working on a project-tracking database. In a data-entry layout for tasks, I'm trying to allow the user to select a Task Category (for example, editing) which is linked to a related database. This Category database has rates, type of units, etc. The user selects their category, enters quantity (of hours, or items) and sees the subtotal of the cost for that task. Like this:

[Category] [Quantity]*[Rate]=[subtotal]

The [rate] is a field displayed from the Category db, and that's where I'm stuck: I'd like to allow users to enter values into that field "on the fly" for tasks that might have a special one-time cost (like a bid or discount) -- but I get the "field not modifiable" error. Is there a more elegant way of handling this? Should I build a script that checks for specific category uses (bid, "specials") and swaps out a different non-related rate field?

Tia!