Every one of the common marketing agency pricing models pays the agency for something slightly different from what you want, and the gap is where the trouble starts.
A retainer pays for time. A project fee pays for a deliverable. A performance fee pays for a number. You want customers at a cost that leaves a margin, and none of the three bills for that directly.
So the question when you compare quotes is less "which is cheapest" and more "which gap can I live with, at the stage my business is at now". It is one of the trickier parts of choosing a digital marketing agency in the UK. This article sets the three models (plus the hybrid most agencies end up offering) side by side, says what tends to go wrong with each, and gives a decision rule by stage.
The prices quoted are UK figures from published research, not our rate card.
What each marketing agency pricing model pays for
A retainer is a fixed monthly fee for an agreed scope. A project fee is a one-off price for a defined piece of work. Performance pricing ties some or all of the fee to a result such as leads, sales or revenue, and hybrids combine a smaller fixed fee with a variable element.
Retainers dominate. In SE Ranking's 2023 survey of 135 marketing and SEO agencies, 32.6% used monthly retainers only and a further 45% combined retainers with other models. Only 11.9% priced by project alone, and 6% used performance-based pricing at all, always alongside something else. The sample is small and 44% of it was continental Europe, so treat the shape as the finding, not the decimals.
On price, UK retainer research from Whito puts a single-channel retainer at £1,250 to £3,500 a month and full service at £3,500 to £16,750, both excluding VAT and ad spend. Expert Market's average single-service retainer is about £960 a month, buying one to three agency days, with an average single-service project at about £1,600. How those agency days compare with a freelancer's is a separate call, set out in freelancer vs marketing agency. Koozai puts micro-business campaigns from £1,000 a month and SMEs at £2,000 to £10,000.
For paid media the common performance-adjacent model is a percentage of ad spend. Adzooma's UK averages put that at 10% to 20% of spend for PPC and 15% for paid social. This is worth separating out, because it is sold as "aligned" and it is the least aligned model on the list.
The four models compared
The table below compares the four models on the things that decide whether a pricing arrangement still works a year in. Those are how predictable the bill is, whose interests the fee serves, who carries the risk, and the failure mode we see most often.
| Retainer | Project fee | Performance or commission | Hybrid (base plus variable) | |
|---|---|---|---|---|
| Predictability of cost | High. Same invoice each month. | High for the quoted scope, low once scope changes. | Low. Good months cost more, and the agency sets the definition of "good". | Medium. The base is fixed, the variable part moves. |
| What the agency is paid for | Availability and hours. | A finished deliverable. | A number: leads, sales, revenue or spend. | Showing up, plus a share of the result. |
| Who carries the risk | The client. You pay whether or not it works. | Shared. The agency eats overruns, you eat anything not in scope. | The agency on paper, the client in practice (see below). | Split, roughly in proportion to the base fee. |
| Incentive problem | Nothing forces the agency to move faster than the retainer requires. | Finish and leave. No reason to care what happens after launch. | Optimise the metric, not the business. Argue about attribution. | The base can be set high enough that the variable part never bites. |
| What usually goes wrong | Scope drifts into maintenance, reporting fills the gap. | Change requests and a second quote for the thing you assumed was included. | Cheap leads, inflated spend, or a dispute over whose sale it was. | Nobody revisits the split once it is signed. |
| Suits | Steady ongoing work: SEO, content, account management. | Defined builds: a website, a brand, a one-off campaign. | Ecommerce with clean tracking and a margin that can afford it. | Most growing businesses, if the base is honest. |
Two of those rows do most of the work. The risk row tells you who is exposed. The incentive row tells you what the agency will drift towards when nobody is watching, which is the part owners tend to miss until month eight.
Where retainers go wrong
Retainers fail slowly, through drift, and there is usually no single bad decision to point at. The agency is paid the same whether it ships three landing pages this month or none, so the work that gets done is the work that is easiest to schedule, and the report gets written to fill the space.
Whito's research notes that twelve-month contracts can be 10% to 15% cheaper per month than rolling ones. That discount buys the agency a year of predictable revenue. It buys you a year of being unable to leave if month four is thin, so the discount only makes sense once you have seen the agency work.
The fix for retainer drift is a written scope that lists outputs, not hours. "Two days a month" is a retainer the agency controls. "Four optimised pages, one technical fix list and a ranking report by the 5th" is a retainer you can audit. We price most ongoing SEO this way, with the deliverables in the contract instead of a day count.
Where project pricing goes wrong
Project fees fail at the edges of the scope. The quote covered the website. It did not cover the redirect map from the old site, the GA4 setup, the cookie banner, or the three rounds of copy changes after the client's partner saw the draft. Each of those is a reasonable change request, and each one arrives as a separate invoice.
The second failure is handover. A project agency's incentive ends on launch day. Whether the site converts in month three is someone else's problem, usually yours. That is fine if you have the in-house capacity to run what was built, and a real problem if you do not.
A project is the right model for a website build or a rebrand, because the deliverable is countable. Ask for the exclusions list before you sign, and ask who owns performance for the first 90 days after launch.
Where performance pricing goes wrong
Performance pricing sounds like the model that cannot hurt you, and it is the one that produces the most disputes. The reason is that someone has to define the result, measure it, and agree it was the agency's doing.
An October 2024 thread on r/LeadGeneration, titled "Commission-based pricing, how do we avoid getting burned?", shows the problem from the agency side. The poster ran an outbound agency on hourly rates, and clients were asking for commission on closed deals. Their worry was simple: they controlled the process up to the booked meeting and had no way to verify what happened after.
The replies are the useful part. One business owner pushed back hard: he had no interest in paying per meeting because, in his words, "I can't feed my family with a meeting", and would only pay for sales. Another agency owner said they had just signed their first commission deal and removed the risk by charging a small monthly fee to cover costs, with an audit clause on the accounts they had introduced. A third suggested splitting the front-end fee so both sides carried the same risk, in return for a share of the back end.
Every one of those replies is describing a hybrid. Almost nobody in the thread thought pure commission would survive contact with an invoice.
The client-side version of the problem is the percentage-of-spend fee on paid media. Chris Avery of Birmingham agency JudeLuxe worked through a 15% fee across two scenarios. At £50,000 of ad spend returning £200,000, the client's estimated profit was £35,000 and the agency fee £7,500. At £100,000 of spend returning £250,000, the client's profit fell to £15,000 and the agency fee doubled to £15,000.
"When the system rewards budget growth rather than profit growth, the system will optimise for budget growth." Chris Avery, JudeLuxe, January 2026
He is careful to say this is a structural problem, not bad faith. An agency on percentage of spend will frame every budget increase as an opportunity and report on ROAS, because that is what the fee rewards. Flat-fee paid media management removes that pull, which is why we do not charge on spend. It is one reason to ask a UK Google Ads agency exactly how it is paid.
Revenue-share deals have their own version. A September 2026 Retail Insider piece on choosing a commission-based agency lists the traps: commission on total revenue instead of growth over a baseline, baselines that ignore seasonality, and revenue growth that disappears once costs are counted. If the agency is paid on December sales and your December was always your best month, you are paying commission on Christmas.
The hybrid, and what it fixes
A hybrid works when the base fee covers the agency's real cost of serving you and nothing more, with the margin coming from the variable part. Whito's UK figures put hybrid bases at £750 to £2,000 a month plus a variable element.
The test is simple. If the base alone would be a comfortable retainer, the variable part is decoration and the agency has no reason to chase it. If the base is thin enough that the agency needs the bonus to make the account worthwhile, the incentive is real.
Hybrids still need the definitions that performance deals need. Which metric, measured where, against what baseline, with what seasonality adjustment, and who can see the data. The Retail Insider piece makes the point that both sides need access to the data used to calculate performance. If the number lives only in the agency's dashboard, it is the agency's number.
A decision rule by stage
The right pricing model depends less on the service and more on how much verified data you have about what a customer costs you. Three common situations:
A new site or a business with no tracking history. Use a project fee for the build and a short rolling retainer (three months, outputs listed) for whatever comes next. Refuse performance pricing at this stage. Neither you nor the agency knows the baseline, so any performance number will be set by guesswork and argued about later.
An established business with steady monthly spend. Use a fixed retainer with outputs in the contract, reviewed quarterly against the outcomes you care about (enquiries, cost per enquiry, revenue where you can see it). If an agency offers a hybrid, accept it only when the base is lower than their standard retainer, otherwise you are paying twice.
Ecommerce brands with clean tracking and a known margin. This is the one case where a real performance element makes sense, because the result is measurable the same way by both sides. Tie the variable fee to profit or to growth over a seasonally adjusted baseline, never to ad spend or to raw revenue. Cap it. Put the data access and the audit right in the contract.
A fourth rule applies to all three. Whatever model you pick, the notice period matters more than the price, which is why it pays to know how to read a marketing agency contract. A model that misaligns incentives is survivable on 30 days' notice and expensive on a twelve-month term.
The question to ask before the price
This question belongs in the proposal stage, alongside everything a serious marketing agency proposal should already show. Before you compare numbers, ask each agency what happens to their invoice if your results halve next quarter. A retainer agency will say nothing changes, and should be able to say what they would do about it. A percentage-of-spend agency will usually suggest more budget. A hybrid agency should be able to show you the month their own fee went down. The answer tells you who is carrying the risk, which is what you are really buying.
If you would like a fixed-fee quote for paid media or ongoing SEO with the outputs written into the contract, get in touch.