Estimate vs invoice: what to send and when
An invoice is a demand for payment for work already done. An estimate is an offer, made before the work, on which nothing is owed yet. That one difference is why a good estimate says valid until instead of due, estimated total instead of balance due, and never subtracts a deposit.
What is the difference between an estimate and an invoice?
An invoice is a demand for payment for work already done; an estimate is an offer to do work at a price, and nothing is owed on it. Everything else follows from that one line. An invoice creates a receivable — it is the document that goes in your books, the one that starts whatever payment clock you keep, and the one you point at if the money never lands. An estimate creates nothing. It sits outside your books until the customer accepts it, and until they do it is a proposal you can still withdraw or reprice. The working test takes a second: if you are asking to be paid for something you have already done, it is an invoice; if you are asking someone to agree to a price before you touch the job, it is an estimate. Send the wrong one and the customer has no idea whether they are supposed to pay today.
Which fields change when a document becomes an estimate?
Seven, and all of them for one reason — nothing is owed yet. Valid until replaces the due date: a deadline to pay becomes a window in which your price holds. Estimated total replaces balance due, because invoice wording on a quote invites someone to pay it on the spot, and now you are sitting on money for a job that is not on the calendar. Estimated tax replaces tax, since it is calculated from figures that are themselves estimates. Payment terms replaces how to pay — you are telling them when money will come due, not collecting it now. Notes, scope and exclusions replaces notes and warranty terms. The deposit stops being subtracted. And the signature line, optional on an invoice, is the entire point of an estimate. Relabel all of it rather than hiding it: nothing anyone typed should disappear because the document type changed.
Why is a deposit subtracted on an invoice but not on an estimate?
Because on an invoice a deposit is money you have received, and on an estimate it is money you are asking for. On an invoice, subtracting it is plain arithmetic — they paid part, the balance is what is left. On an estimate, subtracting it understates the price the customer is being asked to agree to. They sign off on a smaller number than the job actually costs, and the argument shows up later with the invoice. So on an estimate the deposit belongs under the total as its own term, worded like Deposit to schedule, with the estimated total left whole above it. If you quote deposits as a fraction of the job, work the percentage off the total including tax, so half down means half of the number printed directly above it. And never restate a flat dollar deposit as a percentage. That is your software editorialising about your own terms.
Is a quote the same thing as an estimate?
No in principle, and often yes in practice, which is exactly why the document has to say which one it is. A quote or a bid is a fixed price that becomes binding on acceptance; an estimate is an approximation of what the work will likely cost. Plenty of trades use the words interchangeably, and no customer reads the distinction into your header. What actually governs is what the document says about how firm the number is. If the price is firm, say so, and name the scope it is firm for. If it is an approximation, say what it is based on — what you could see at the walkthrough — and name the conditions that would change it. Two sentences of that are worth more than any word at the top of the page. The heading is a title; the sentence is what a customer reads back to you three weeks later.
How long should an estimate stay valid?
Long enough to give the customer a real decision, and no longer than your own supplier will hold their price. Valid until is the field that protects you when material costs move, and it is the field most estimates leave blank. The honest anchor is the supply house: if the counter quoted you a price good for two weeks, an estimate that stands for two months is a promise you cannot keep, and you will either absorb the difference or reopen a price the customer has already accepted. Trades whose materials move fastest — anything priced off copper, lumber, fuel or refrigerant — need the shortest windows. Write a real calendar date rather than a phrase, because good for 30 days on an undated page is both unprovable and unmemorable. And do not let software fill this in for you. How long your price holds is a business decision, and nobody else can make it.
Should sales tax appear on an estimate?
Yes, when the job is taxable — leaving it off manufactures the exact dispute a written estimate exists to prevent. A customer who agrees to a pre-tax figure and then opens an invoice with tax added on has, from their side of the counter, watched the final bill exceed the estimate. Label it Estimated tax and put the full figure in front of them while they are still deciding. Taxability follows the kind of work and where you do it, not the title on the document; in most states a job that improves real property is handled one way and a plain repair another, and nothing about that shifts when the estimate becomes an invoice. Confirm it with your state revenue department rather than a web page. If you genuinely quote pre-tax, write that on the document in words, so the number and the expectation agree.
Why does an estimate need a signature line and an exclusions block?
Because a signature is how an offer becomes acceptance, and exclusions are what stop the later argument that the acceptance covered something else. An estimate is an offer; until somebody signs it you have a proposal and they have a piece of paper. A dated signature also anchors the validity window, so valid until refers to something you can point at. Exclusions do the other half of the job. What a price includes is obvious to you and invisible to the customer; what it excludes is where every dispute lives. Name the categories your trade actually argues about — what is behind the wall or under the surface, permit and inspection fees, disposal of whatever you find, code upgrades the repair triggers, restoring finishes you had to cut, access and parking, and materials at today's price. A short exclusions list is not defensive. It is the cheapest insurance on the page.
Common questions
Is an estimate legally binding?
An estimate is an offer, so by itself it generally binds nobody. What binds is acceptance — a signature, a deposit paid against it, or work started on its terms — and what it binds you to is whatever the document actually says. A bare number with no scope, no exclusions and no expiry is the version most likely to be read as a firm price. Consumer rules for home improvement work vary a great deal, and some places require written agreements or limit deposits, so check your own state rather than assuming.
What if the final bill comes in higher than the estimate?
Put the difference on its own line with the reason on it, and never fold it quietly into the hours. Where you can, get the change agreed before you do the work: a short written change order referencing the estimate number is enough, and a text message with a number in it has settled more of these than any contract ever has. Invoicing an overage the customer is seeing for the first time is how a good job turns into a collections problem.
Should estimates and invoices share the same numbering?
Keep them on separate sequences if you can. Estimate 1042 and Invoice 1042 are two different documents about what may be two different scopes, and one sequence for both makes your own records ambiguous the moment an estimate is declined. The number field is yours to type into, so nothing stops you running estimates on their own run of numbers. When an estimate becomes a job, reference the estimate number on the invoice rather than reusing it. That one line is what lets you, and the customer, line the two documents up a year later.
Can I turn an estimate into an invoice?
Yes, and the safe way is to rebuild it from the estimate rather than editing the header. Three things have to change: the deposit flips from asked-for to received and starts being subtracted, valid until becomes a due date or payment terms, and any work that was not on the estimate goes on its own described line. If the scope changed, show the estimate's scope and the additions separately rather than one new total that no earlier document explains.
Does an estimate need a due date?
No, because nothing is due. What it needs is a valid-until date, which answers a different question: how long your price holds, not when money is expected. If a deposit is required to get on the schedule, that belongs under the total as a term, not as a balance. A due date on a document nobody owes anything on is the quickest way to have somebody pay in full for a job you have not started.