Estimate vs invoice: the difference, and when each one binds you
Two documents, two moments, two legal weights
An estimate is a proposal: it describes work and a price, and commits nobody until it is accepted. An invoice is a claim for payment: it certifies that work was done (or a deposit is due) and creates a debt.
When does an estimate become binding?
The moment the client accepts it — a signature, but in many places a clear written "go ahead" referencing the estimate also counts. From then on:
- you are bound to the described work at the stated price, until the validity date;
- the client is bound to pay it once the work is done.
That is why the validity date and the exact scope matter so much. Anything outside the scope needs a change order, not a verbal agreement.
When should you invoice?
- Deposit invoice as soon as the estimate is signed, if you require one.
- Final invoice the day the job is finished — not next week. Every day of delay statistically pushes the payment further.
- On long jobs, progress invoices at agreed milestones keep your cash flow alive.
Numbering: one sequence, no gaps
Invoices must be numbered sequentially without holes — that is what tax authorities check first. Estimates deserve a sequence too (EST-2026-0042), because "the estimate of last Tuesday" is not a reference.
The clean workflow
- Estimate sent (numbered, validity date)
- Client signs — ideally electronically, timestamped
- Deposit invoice → deposit paid
- Work done, photos taken
- Final invoice the same day, balance due
Pro Speak Artisan runs this exact pipeline: the signed estimate mints the invoice with frozen totals and a sequential number, and payment can be requested in one tap. More on the blog.