Check marketing agencies return on investment before you renew

When renewal reaches the decision point

This worked example is illustrative: the client and every figure are invented to show the method. Renewal comes due while the client is reviewing one campaign, rather than judging the agency from a broad dashboard impression.

The parties have named revenue attributed to a particular channel as the main outcome, with qualified leads as supporting evidence. The starting fee position and access to account and finance records were agreed before delivery began.

The client asks whether the measured commercial result warrants another term. A target, volume of activity or favourable platform total cannot settle that question alone. The agreed outcome gives the meeting a test, while the selection checklist helps keep account data access and financial records within the decision from the start.

Building the cost record

Before comparing outcomes, the client rebuilds the monthly cost record from invoices and internal records. It includes the retainer, media, any agency-billed tools and internal review time, even where no invoice covers staff effort.

The hidden costs and cost guide help separate the stated fee from the full cost of delivery.

VAT changes the cash comparison. The £10,000 total here is net of VAT. A client that can reclaim VAT keeps the net figures. A client that cannot reclaim it adds VAT to the agency charges, so a £5,000 monthly retainer becomes £6,000 at the standard 20 per cent rate, and the ratio is recalculated on the higher cost. The client checks the current VAT rates, then applies one basis consistently. VAT alters the cost used in the calculation, not the measured campaign result.

Testing the return against records

With costs assembled, the client compares the agency dashboard with the CRM and identifies which record supports each measure.

The reporting metrics keep discussion tied to the commercial outcome agreed at the outset. A dashboard total remains evidence to reconcile, rather than a verdict or a substitute for the primary result.

The calculation uses incremental gross profit divided by total agency cost, with the same attribution method throughout. In this scenario, £30,000 in gross profit against £10,000 total cost gives a 3:1 result. The client accepts that ratio only if the method for identifying incremental profit remains consistent between review periods.

Be clear what the 3:1 is. It is a benefit-cost ratio: £3 of gross profit for every £1 of agency cost. Conventional ROI subtracts the cost first: (£30,000 − £10,000) ÷ £10,000 = 200%. Both describe the same result, so state which one you are quoting.

Alongside the ratio, the client records payback as the period until cumulative gross profit covers cumulative cost. As an illustration, suppose the £10,000 is spent in month one and the £30,000 gross profit arrives evenly over six months, £5,000 a month. Cumulative profit covers the cost at the end of month two, so payback is two months. Keeping ratio and payback together makes the result easier to compare over time, while changing attribution midway weakens that comparison. Supporting measures add context, but do not displace the commercial result agreed for the renewal decision.

Making the renewal call

The client shares the ratio, payback period and cost breakdown with the agency before the meeting. The agency is asked to confirm the cost side, and the discussion uses underlying records as well as the headline result.

Relationship quality, review cadence and scope help frame the choice, but do not replace evidence of performance.

The client checks the commercial contract terms alongside the calculation because scope changes can alter costs. Where renewal discussion turns on claims in agency promotional material, the client treats those claims as a separate matter and checks the advertising rules. Any proposed charge is checked for its reason and the circumstances in which it applies.

The legal reference depends on who the client is. The Consumer Rights Act 2015 covers contracts between a trader and a consumer, and its care and skill requirement applies to consumer contracts. A company hiring an agency is normally not a consumer, so its agreement is governed by its own terms and, for the implied duty of reasonable care and skill, the Supply of Goods and Services Act 1982. Record which applies alongside the campaign evidence.

On the scenario result, renewal is supported if the 3:1 return holds and the working relationship remains sound. If performance is sound but costs have drifted, the client can renegotiate. If results remain stalled despite agreed changes, leaving is an option. The budget template keeps fees, media and internal time visible for that decision.

Rules carried forward from the case

The client carries one discipline into the next term: renewal follows the agreed outcome and a complete, consistently measured cost record, not the most flattering dashboard line. The scenario shows why the ratio is useful only after its cost base and attribution method have been checked against underlying evidence.

For continuing work, the client keeps read-only access to advertising accounts and analytics so the evidence can be checked independently of a single agency report. The account data access is retained with the cost record, and the agency is given a reasonable time to confirm entries before the next review meeting.