The bid's sales-tax treatment is locked, and explains itself

When a bid is created, its sales-tax treatment and rate come from the state the job is in — tax on materials in California, on top of every line in Washington, none in Oregon. That made the picker on the estimate easy to change by accident and hard to read: four short labels, no explanation.

It now explains itself. Hover any option and it says where the rate sits in the math and what the customer sees. While the control is unlocked, the selected treatment's full description reads below the controls, so the explanation is never hover-only.

And it stays locked. The treatment and rate open only after you click the lock beside them, which tells you where they were seeded from. Lock it again when you are done; every new visit to the bid starts locked. The exemption on file still zeroes the rate on its own, locked or not.