The short answer
Extra work becomes unpaid work at a specific moment: when you do it before anyone has priced it. Everything that follows is recovery, and recovery is harder than the 10 minutes it would have taken to stop and say so.
Notice the request as a request, rather than as a detail of the work already agreed.
Say so the same day, before you start it, and in writing.
Price it, even where the price is zero, so the client sees what it cost.
Get a short written approval back, and amend the purchase order if there is one.
Invoice it separately, so it can be approved separately.
The useful shift is treating extra work as a small new sale rather than as a favour granted mid-project. A sale has a price and a yes. A favour has neither, and turns up later as a disputed invoice.
How common this is
It is close to universal. In PMI's 2018 Pulse of the Profession, 52% of projects completed in the preceding 12 months had experienced scope creep or uncontrolled changes to scope, up from 43% 5 years earlier. PMI's own definition is worth keeping, because it names the mechanism: the expansion of scope without adjustments to time, cost and resources.
The adjustment is the whole point. Scope growing is normal and often good for the work. Scope growing while the price, the deadline and the team stay fixed is the part that ends up on your side of the ledger.
What actually counts as extra work
Most arguments about scope are really arguments about whether something was already included, and they happen because nobody defined the boundary. A practical test, applied at the moment the request lands:
Was it written down? If the proposal or statement of work does not describe it, it is extra until someone agrees otherwise.
Does it add time? If it costs you more than about an hour that you had not planned, it is extra.
Is it a revision or a redirection? Revisions inside an agreed round are included. Redoing work because the brief changed is not.
Would you have priced the job differently? If knowing this at proposal stage would have changed your number, it is extra.
The grey area is the small request that is genuinely small. A logo resized, a headline reworded, a file exported again. Absorb those and absorb them gracefully; the goodwill is worth more than the 15 minutes. The problem is the 30th small request, which is why the point below about a running log matters more than any single conversation.
Why agencies absorb it anyway
Knowing the boundary and defending it are different skills, and the reasons for not defending it are usually sound ones:
The relationship feels too new, or too good, to introduce friction.
The request arrives mid-flow and saying yes is faster than explaining.
The extra work is interesting, and you want to do it.
There is a fear that raising money mid-project reads as difficult.
The amount feels too small to be worth a conversation, several times over.
The last one compounds. 20 uncounted small requests across a 3-month project is a week of unbilled work, which on a $15,000 project is most of the margin. Counting them is what makes the pattern visible, to you and to the client.
Say it the same day
The single highest-value habit here is speed. A request flagged within hours is an ordinary planning conversation. The same request raised at invoicing is a complaint about something the client believes they already have.
The message can be short, and it works better when it leads with yes:
Subject: Re: adding the second landing page
Hi [Name],
Happy to take the second landing page on. It sits outside what we scoped, so I want to price it before I start rather than surprise you later.
It's roughly [X] hours, so [amount], and it would move delivery to [date]. Alternatively we can keep the original date and run it as a second phase.
Reply with a yes and I'll add it to the plan today.
Thanks,
[Name]
3 things are doing the work. The answer is yes, so the client does not have to argue you into it. The cost is given in both money and time, since a deadline is often the thing they care about more. And the approval requested is a single word, which is the largest ask most clients will reliably complete by email.
What a change order needs to contain
For anything substantial, the reply above becomes a short document. It does not need to be formal, and 1 page is usually enough:
Element | Why it is there |
|---|---|
What is changing | Described in the client's words, so they recognise it |
Why | Who asked, and when, which settles the argument later |
Price and how it is calculated | Fixed, hourly, or a rate card line |
Effect on the schedule | Often the part that changes the client's answer |
What it does not include | Prevents the change order from growing its own scope |
Payment terms | States whether it bills now or with the next invoice |
Approval | A name, a date, and a reply saying yes |
Number them. Change order 01, 02, 03 against the project. A numbered series is easy to reference on an invoice, easy for the client's finance team to match, and quietly communicates that this is a process rather than a complaint.
Pricing it
3 approaches, each of which suits a different situation:
A fixed price for the change. Cleanest for a well-defined addition. The client knows the number before they say yes.
Time and materials against a cap. Right when the work is genuinely open-ended. The cap is what makes it acceptable to a client who fears an open meter.
A published rate card. Best for clients who make frequent small requests. It converts every future negotiation into arithmetic.
Do not discount the extra work to smooth the conversation. A change order priced below your normal rate teaches the client that work requested late is cheaper than work requested at proposal stage, which is the opposite of the incentive you want. If you want to give something away, give it away visibly: put the price on the change order and show it discounted to zero.
When the work is already done
This is the common case and it is recoverable, though less cleanly. The goal is to get the extra work acknowledged before you invoice it, because an unexpected line on an invoice reads as a billing error.
Reconstruct the record first. Find the messages where the work was requested, note the dates, and write down what it actually took. Then raise it as a conversation rather than as a bill:
Subject: Project scope — a conversation before I invoice
Hi [Name],
Before I send the final invoice I want to flag something rather than put it on there unannounced.
Since we agreed the scope in [month], we've added [item 1], [item 2] and [item 3], all requested on [dates]. Together that's about [X] hours beyond what we scoped, which at our rate is [amount].
I should have raised each one at the time, and that's on me. What I'd suggest is [billing half of it / adding it to the next phase / absorbing it and agreeing a change process from here].
Can we talk it through this week?
Thanks,
[Name]
Taking part of the responsibility is what makes this land, and it happens to be accurate. Offering a route other than the full amount gives the client somewhere to go that is not a refusal. Many will take the middle option, and the ones who take the cheapest option have still agreed a process for next time, which is worth more than the invoice.
The 2 places this breaks quietly
Retainers and purchase orders are where absorbed extras stop being visible at all.
On a retainer, the monthly fee hides the growth. The scope expands month by month and the invoice stays the same, so nothing prompts a conversation. The fix is a stated capacity, in hours or in deliverables, and a short monthly note showing what was used against it. See the pattern of a client who behaves the same way every month for the related habit of looking at the series rather than the single invoice.
With a purchase order, the failure is mechanical. An invoice above the purchase order value fails the match and stops, whatever your contact agreed verbally. Get the purchase order amended before you deliver the extra work, for the reasons set out in the guide to PO numbers on invoices.
Where the law lands
Most agency contracts say variations must be agreed in writing. Whether that clause protects you or traps you depends on which side of it you are standing.
In the US, the general position is that a written-modification requirement is enforceable, with an important qualification: conduct can waive it. The Uniform Commercial Code, which governs sales of goods rather than services, puts the principle plainly at section 2-209, where a modification that fails the formal requirement can still operate as a waiver. Service contracts sit under state common law, where courts have similarly found that a client who repeatedly requests and accepts extra work can waive the written-change-order clause they themselves insisted on. That cuts both ways, and it is a reason to keep the messages where the work was requested.
In the EU, contract variation is national law rather than anything harmonised, so the answer depends on the country in the contract. In the UK, the courts have gone the other way and enforced these clauses strictly: in Rock Advertising v MWB Business Exchange Centres [2018] UKSC 24, the Supreme Court held that a clause requiring variations to be in writing and signed meant what it said, and an agreed oral variation did not take effect. If your contract is governed by English law, the written change order is the thing that exists.
Either way the practical answer is identical, which is the useful part: get it in writing at the time.
Making it routine
Agree the change process when you agree the work, alongside the other questions worth settling before you start. Name who can approve a change on the client side, since a request from someone without budget authority is the most expensive kind. Keep a running log of every request against the project, including the ones you absorb, and show it at the end. Clients are rarely trying to get free work, and a log of 22 absorbed requests changes the next proposal more effectively than any conversation about respect.
FAQ
How do I tell a client something is out of scope without annoying them?
Lead with yes, then give the price and the schedule effect, then ask for a 1-word approval. The friction comes from clients feeling refused, so make the answer an option rather than a rejection, and raise it the same day the request arrives.
Can I charge for scope creep after the work is finished?
You can ask, and it often works, but raise it before the invoice rather than on it. Show the dates the work was requested, take some responsibility for not flagging it sooner, and offer a middle option such as billing part of it or carrying it into the next phase.
What if the contract says changes must be in writing and I did the work anyway?
In the US, a client's repeated requests and acceptance of the work can waive that clause, though it depends on your state and the evidence. Under English law the clause is likely to hold after Rock Advertising. In both cases the messages showing the work was requested are the thing that matters, so gather them before you raise it.
Should I give small extras away for free?
Yes, up to a point, and visibly. Put them on the change order or the log at full price and show them discounted to zero. The client sees the value, and you keep the count.
How do I stop scope creep on a retainer?
State the monthly capacity in hours or deliverables and report against it each month. Without a stated ceiling the scope expands while the invoice stays flat, and nothing in the process prompts a conversation.
Who at the client should approve a change order?
Whoever holds the budget, which is frequently not the person making the request. Establish this at the start, because approval from someone without spending authority gives you no protection when the invoice reaches finance.
Not legal advice. Contract law on variations differs by state and by country, and the position depends on the wording you have signed — take advice on anything contested.