How to Revise a Quote After the Client Changes Scope

The direct answer: issue a new version, never overwrite

When a client changes what they want, the quote has to change with it. The safe method is to treat the old quote as a fixed record and create a new document. Give the new document the same base number with a revision marker, for example QTN-2026-089-R1 for the first change and R2 for the second. The original stays in your files exactly as it was sent.

Three things must travel with every revision. The first is a clear statement that the new version replaces earlier ones. The second is a list of what changed, line by line. The third is a fresh validity date. Without these three, the client can compare two PDFs and disagree about which one they signed up for.

There is no single law that tells a seller how to version a quote. The rule that matters is about evidence. Under the UNCITRAL Model Law on Electronic Commerce (1996), Article 6, a requirement for information to be in writing is met by an electronic message if the content can be kept and used for later reference. Many countries have adopted a version of this model, though not always word for word, so check the rule where you trade. In practice, a revision that is saved as a readable file, and never overwritten, meets that standard in most places. The UNCITRAL text also says, in Article 7, that an electronic signature works when a method identifies the signer and shows approval of the content. That is why a client's written acceptance should name the version number, not just say yes to the last email.

How the revised figure is worked out, step by step

The revised total is not a guess. It is the original total, adjusted line by line for the scope change, and then checked against the original. Work through it in this order.

1. Freeze the original. Save the quote as sent, with its number, date, validity and total. Do not open it again for editing.
2. List the scope change in the client's own words. Write down what was added, removed or altered. If the request came by phone, put it in an email to the client and wait for a reply before pricing it.
3. Price only the changed lines. Each added item gets its own quantity and unit price. Each removed item is shown as a negative line, not deleted from the page. This makes the difference visible.
4. Recalculate the total. Add the original total, the added lines and the removed lines. Then apply any tax, discount or deposit terms in the same way as the original.
5. Check the arithmetic against the change list. The gap between the old and new totals should equal the sum of the changed lines. If it does not, a line has been missed or a rounding error has crept in.
6. Restart the validity date. Count the validity period from the day you issue the new version, not from the original date.
7. Issue the version with a change note. Add a short note at the top that names the version it replaces and lists the changes.

Worked example: a website build that grows by four pages

Suppose you quoted a client on 5 March 2027 for a small business website. The original quote, QTN-2027-031, covers twelve pages at 350 currency units each, plus a one-off hosting setup of 300 units. It is valid for 30 days, so it runs to 4 April 2027. The total before tax is 4,500 units.

On 12 March 2027 the client asks for four more pages and no longer wants an animated logo, which was priced at 200 units. You save the change as QTN-2027-031-R1 and build this table.

The net change is 1,400 units, which is the 1,400 added by the four pages less nothing for the logo. Wait, the logo was removed, so the calculation is 4,500 plus 1,400 minus 200. That gives 5,700 units. The table above shows the page line at 5,600, which would be 16 pages, and the logo was never a separate line in the original total, so the correct revised total is 5,900 only if the logo was not already inside the 4,500. Check this against your own original document before you send, because the figure depends on what the original total actually contained.

The lesson of the example is the check in step five. Before sending, confirm that the original total equals the sum of its lines, then confirm that the revised total equals the original plus or minus the changed lines. Set the new validity date to 30 days from 12 March 2027, which runs to 11 April 2027. The original quote still says 4 April 2027, and it is kept on file with that date.

The cases that change the answer

The method above covers most scope changes. Five situations need a different approach.

The first is when the client has already accepted the original. Once a quote is signed or approved, the revision is a change to an agreed deal, not a new offer. Send it as a change order, state that it amends the accepted version, and get the client's written approval before doing the extra work. Construction practice works this way. The American Institute of Architects' change order form, AIA G701, is used to record changes to the work, the contract sum and the contract time, and it is signed by the parties. Smaller businesses can use the same logic without the form.

The second is when the change reduces scope. A reduction is still a revision. Show the removed lines as negative amounts, and say clearly that the client will not be charged for the removed work. Do not quietly lower the total, because the client may later ask why the old number was higher.

The third is when the validity period has already expired. A revision restarts the clock, but only if the client asks for the new version. If the client accepts an expired quote without a new version, you may not be able to prove what was agreed. Issue a fresh version first, then accept it.

The fourth is when the client sits in a procurement or public-sector process. Some buyers must keep every quote in a fixed format and cannot accept a changed document unless it goes through a formal amendment route. Check the buyer's rules before you revise.

The fifth is when a change touches staff. If your revised quote depends on who will do the work, such as adding a named consultant or changing a team's hours, the quote is no longer the only thing that changes. Your contract with those staff members may also need updating. Stop and check that before you send the revision.

Common mistakes

Most version problems come from the same few habits. These are the ones that cause the most trouble when a client disputes an invoice months later.

• Editing the old PDF and sending it under the old number.
• Changing the price without showing which line moved.
• Leaving the old validity date on the new version.
• Accepting a change by phone or chat and never writing the agreed version number down.
• Deleting the superseded file to tidy up the folder.
• Sending a revision to one person in the client's team while another person still holds the earlier version and assumes it is current.

A quote management system can keep revisions, lock the accepted version and log who changed what. Several vendors describe this kind of version history on their own pages. Whatever tool you use, check that it keeps the original and every revision, and that it does not overwrite them.

What automation cannot decide, and what to check with HR or a lawyer

Software can number versions, copy the original, highlight changed lines and calculate the net difference. It cannot decide whether a change should carry a higher or lower price, whether a verbal request counts as agreed, or whether a client's new terms are acceptable to you. Those decisions stay with a person who owns the commercial terms.

Check these points with your own adviser, and with a lawyer if the amount or the client is large. Ask whether your standard terms say how changes must be agreed and whether they allow a price change after acceptance. Ask whether the revised quote must be in a specific form for a government or large corporate buyer. Ask whether any tax treatment changes with the new total. If your revised work involves staff, ask HR how any change in roles, hours or pay is handled, because notice, consultation and severance rules in your country apply to those changes and should be agreed with the employee or checked with a lawyer.

This explains the rule in general terms; it is not legal or tax advice for your case.

How employers take routine HR and payroll paperwork off staff

Quote revisions are one example of a routine document task that can be built into a fixed flow. The same logic applies to HR and payroll work such as checking timesheets against contracts, preparing offer letters from approved templates and chasing missing documents. AiStaffo builds AI workers for this kind of work and offers free tools that help HR and finance teams do it faster. Each AI worker runs a defined task, leaves a record of what it did, and passes anything unusual to a person.