The number changed. Say why in one or two lines, then send the new total. Don’t hide it.
Put in the real estimate, final, and what drove the change.
A little under
Good news — you came in lower.
Hi Jordan — final invoice is $180 (estimate was $210). Materials came in under what I quoted. Invoice is attached.
A little over
Use when you found more work and already told them.
Hi Alex — final is $320. Estimate was $275; the extra was the damaged trim we talked about on-site. Invoice attached — happy to walk through the line items.
Same number
Close the loop when nothing moved.
Quick note: final invoice matches the $240 estimate. No surprises. It’s attached whenever you’re ready.