Quote, estimate or invoice: which one to send and when
Three documents that get used interchangeably and should not be. The difference decides whether you can charge more when the job turns out bigger than it looked.
A quote is a fixed price you are committing to, an estimate is your best considered guess that can change, and an invoice is the demand for payment once the work is done. Send a quote when the scope is genuinely known, an estimate when it is not, and never let a customer treat an estimate as a quote by accident.
A quote is a price you are agreeing to hold
A quote is a firm offer to do defined work for a stated price, and once the customer accepts it, that is generally the price.
This is why the scope on a quote matters as much as the number. "Replace consumer unit, 1,450" is a commitment with no boundaries. "Replace consumer unit with 12 way board, including 6 AFCI devices, testing and certification, based on existing cabling being serviceable" is a commitment with a visible edge. If the cabling turns out not to be serviceable, you have somewhere to stand.
Two things every quote should carry. A valid until date, because material prices move and a quote from four months ago should not still be binding. And an explicit statement of what is not included, which is the single most useful sentence on the document. Whatever you leave unsaid will be assumed to be included.
An estimate is a considered guess, and it must look like one
An estimate is your best assessment of likely cost when the full scope cannot be known yet, and it is expected to move.
Estimates suit work where the truth is behind a wall, under a floor or inside a machine. Fault finding, drain problems, older properties, anything where the first hour changes what the next ten look like. The mistake is not sending an estimate. It is sending one that reads exactly like a quote.
Make it unmistakable. Head the document Estimate, state what it is based on, and give the customer a rule for what happens when reality differs. A sentence like "This is an estimate based on what is visible today. If the run needs replacing rather than repairing, I will stop and confirm the additional cost with you before continuing" is worth more than a paragraph of terms, because it tells the customer they will not be surprised.
Legally, the weight of these words varies by country, and in some places customer protection rules limit how far an estimate can be exceeded without agreement. Treat that as a local question, and treat the clear written boundary as universal good practice.
The invoice is the only one that asks for money
An invoice is issued after the work, or after an agreed stage of it, and it is the document that creates the debt.
This is the practical distinction that matters for your bookkeeping. A quote that is never accepted is nothing. An invoice that is never paid is an unpaid debt that belongs in your records. Mixing them up produces books that either overstate what you earned or lose track of what you are owed.
The cleanest workflow is one document turning into the next. Quote, accepted, converted to an invoice with the same lines and the same numbers, plus any deposit already deducted. Retyping a quote as a fresh invoice is where a digit gets dropped and an argument begins. The nine elements an invoice must contain are set out in the guide on writing an invoice.
The three documents side by side
If you remember one row from this table, make it the last one.
| Quote | Estimate | Invoice | |
|---|---|---|---|
| Sent when | Before work, scope known | Before work, scope unclear | After work or a stage |
| Price is | Fixed once accepted | Expected to move | Final and owed |
| Needs a date | Valid until | Valid until | Issue and due date |
| Creates a debt | No | No | Yes |
| Biggest risk | Scope you did not exclude | Reading like a quote | Going out days late |
The other pattern worth stealing: quote the part you can see and estimate the part you cannot, on the same document, clearly separated. "Fixed price for the panel replacement, plus an estimate for any remedial cabling found once the wall is open" is honest, easy to read, and protects both sides.
Where deposits and staged payments fit
A deposit belongs to the quote stage, and it should be recorded against the job so the final invoice deducts it automatically.
The case for deposits is not distrust. It is that on any job where you buy materials up front, the alternative is funding the customer's project out of your own account for a fortnight. A boiler, a switchboard, forty square metres of paving. That money is yours until the balance is paid, and a deposit simply stops you carrying the risk alone.
For longer work, stage the payments against milestones the customer can see rather than dates on a calendar. Materials delivered, first fix complete, commissioning done. A stage tied to visible progress rarely gets argued with, while a stage tied to a Tuesday does.
Practically, this is where converting a quote instead of rewriting it pays off. Trades that quote and stage most often, such as HVAC contractors and landscapers, are the ones where a retyped figure causes the most damage.
What to do when the job grows mid way
Stop, put the extra in writing, and get a yes before you carry on. Every time.
The trap is that stopping feels rude when you are standing in someone's hallway and the fix is twenty minutes of extra work. So you do it, mention it later, and now the customer is being asked to pay for something they never agreed to. From their side that is a bigger breach than the money, because it is a surprise.
A message is enough. "The isolation valve is seized so the run needs replacing rather than repairing, that is an extra 140 and about an hour. Happy to go ahead?" Sent from the property, answered in two minutes, and it now exists in writing. When the invoice arrives with a variation line on it, the customer already knows why.
On the invoice, keep variations visually separate from the quoted scope. Original lines, then a clear break, then what was added and agreed. A customer scanning for surprises will find the section that explains itself, which is exactly what you want them to find.
Making the right document the easy document
People send the wrong document because the right one is more work, so the fix is to make them equally quick.
In Invoice Local a quote and an invoice are the same builder with a toggle. The quote carries a valid until date instead of a due date, gets its own number series, and stays out of your outstanding totals so it never inflates what you think you are owed. When the customer accepts, one tap converts it, the lines carry over, the deposit is deducted and a fresh invoice number is assigned.
That removes the excuse. If sending a proper quote costs the same thirty seconds as texting a number, the number in the text message stops happening, and with it goes most of the fixed price arguments that follow.
Questions people still ask
Is a quote legally binding?
In most places an accepted quote forms a contract at that price, which is exactly why the scope on it matters. The detail varies by country, so if a specific job carries real risk, take local advice rather than relying on a general answer from a website.
Can I charge more than an estimate?
Usually yes, because an estimate is not a fixed price, but there are limits in some jurisdictions and there is always a limit to how far a customer will follow you. The reliable protection is telling them before you exceed it, not after.
Should a quote include tax?
Show the price the way the customer will be billed. For a domestic customer, quoting the total including tax avoids an unpleasant surprise at the end. For a business customer who reclaims tax, quoting net is normal. Either way, say which one you are showing.
How long should a quote stay valid?
Long enough for the customer to decide and short enough that a material price move does not land on you. Thirty days is a common default. On jobs with heavy material content, shorter is reasonable, and saying so on the document is better than withdrawing it later.
Do quotes and invoices need separate numbering?
It helps. A separate prefix for quotes keeps your invoice sequence clean, which is what your accountant cares about, and it removes any chance of a quote being mistaken for a bill by an accounts department.
Related guides
The same paperwork, trade by trade
The trade pages show Invoice Local doing this in context, with real line items and the wording each trade uses. There is also a free invoice template if you would rather start from a blank document.
Send a quote in the time a text message takes
Quotes and invoices use the same builder in Invoice Local, with one tap to convert an accepted quote and the deposit already deducted.