Quote vs estimate vs invoice

Call an estimate a quote and you can be held to a number you guessed in a driveway. Three documents, three different promises. Get the words right and most pricing disputes never start.

A quote is a promise

A quote says: this work, this price. Once the customer accepts it, you're expected to stand behind that number even if the job takes longer than you hoped. That's not a trap, it's the deal - the customer gets certainty, you get the job.

The protection is in the detail. Spell out what's included, what's excluded, and how long the price stands. If the job changes once you're in - they want an extra powerpoint, the deck grows a metre - that's a variation. Put the new price in writing before doing the extra work, not on the final invoice as a surprise.

An estimate is an educated guess

An estimate says: probably around this, but I can't see behind the wall yet. It's the right tool when the job has unknowns - old wiring, hidden water damage, stumps of mystery depth. The actual price can move as the job reveals itself.

Two rules keep an estimate honest. Label it "Estimate", not "Quote". And say plainly on it that the final cost may change once the work opens up. Then, once you can see what you're dealing with, firm it up into a real quote.

An invoice is the bill

An invoice comes after the work (or at agreed stages during it) and says: here's what you owe and when it's due. It's the only one of the three that asks for money, and the only one with legal formatting rules - here's exactly what has to be on it.

Which one, when

• You can see the whole job and price it with confidence: send a quote
• Real unknowns you can't inspect yet: send an estimate, firm it into a quote once you can see
• Bigger job? Put deposit terms on the quote itself
• Work done: send the invoice the same day, while the job's still warm

Why the fuss over one word? Because the customer heard "quote" and locked the number in. If it grows with no paper trail, you're arguing from the weaker side, and if it lands at a tribunal, the document with the wrong name is the evidence. Cheap insurance: use the right word, keep copies for 5 years.