Hiring an ads agency feels like the obvious move when Google Ads gets complicated. You hand over the account, pay the retainer, and assume someone qualified is watching the numbers. After running a marketing agency for nine years, we can tell you that assumption deserves more scrutiny than most business owners apply to it.
This article breaks down what an ads agency actually delivers, what it typically costs, where the model tends to fall short for smaller businesses, and why an AI agent is becoming a credible alternative for SMEs who want active account management without the overhead.
What an Ads Agency Does (And Doesn't Do)
An ads agency manages paid advertising on behalf of clients. In the Google Ads context, that means setting up campaigns, choosing keywords, writing ad copy, adjusting bids, and reporting on performance. The agency earns a fee — either a flat monthly retainer, a percentage of ad spend, or both.
What the model often doesn't include, particularly at the lower end of the market, is daily account activity. Many agencies batch their optimisation work into weekly or fortnightly sessions. Your campaigns run unsupervised the rest of the time, which matters more than most clients realise. A poorly performing ad group can bleed budget for days before anyone looks at it.
The quality gap between agencies is also significant. A senior account manager at a reputable firm brings genuine expertise. A junior account executive at a high-volume agency, managing forty accounts simultaneously, brings considerably less. The retainer price rarely tells you which one you're getting.
For context on what active Google Ads management actually involves day to day, the mechanics matter as much as the strategy.
Ads Agency Pricing: What SMEs Actually Pay
Agency pricing for Google Ads management follows a few common structures. Understanding these before signing anything will save you from an awkward conversation three months in.
| Pricing Model | Typical Range | What to Watch For |
|---|---|---|
| Flat monthly retainer | £500–£2,500/month | Low-end retainers rarely cover active daily management |
| Percentage of ad spend | 10–20% of spend | Incentivises higher spend, not better performance |
| Performance-based | Varies widely | Definitions of "performance" vary — read the contract |
| Setup fee + retainer | £500–£1,500 setup | Often non-refundable even if results disappoint |
For a small business spending £2,000 a month on Google Ads, a 15% management fee adds £300 monthly. That's £3,600 a year for account management — reasonable if the work justifies it, poor value if the account is checked twice a month. For a fuller breakdown of what these fees cover, PPC management fees for SMEs is worth reading before you commit.
The percentage-of-spend model deserves particular scepticism. An agency paid on percentage has a structural incentive to recommend increasing budget, regardless of whether the existing budget is being used efficiently. We saw this pattern repeatedly during our agency years, and it's not always cynical — agencies genuinely believe more spend equals more results — but the incentive misalignment is real.
What the Ads Agency Model Gets Right
Fairness matters here. There are genuine reasons to use a good ads agency, and dismissing the model entirely would be inaccurate.
Strategic thinking is the most legitimate one. A senior PPC specialist who has managed accounts across multiple industries brings pattern recognition that takes years to develop. They'll spot structural account problems, identify audience gaps, and know which campaign types suit which business models. That kind of judgment is difficult to replicate without experience.
Creative input is another genuine advantage. Ad copy, landing page recommendations, and audience segmentation benefit from human judgment that understands brand voice. Automated systems optimise within parameters; they don't rewrite your value proposition.
Agencies also handle the administrative burden — tracking setup, conversion configuration, Google Merchant Centre troubleshooting — that consumes hours if you're doing it yourself. For SMEs with no internal marketing resource, that has real value.
The honest trade-off is that these benefits are most reliably available at the higher end of the agency market, at fees that many SMEs find difficult to justify relative to their ad spend.
Where the Ads Agency Model Struggles for SMEs
The agency model was designed for clients spending significant budgets — traditionally £5,000 a month and above. Below that threshold, the economics become awkward for both sides. The agency can't profitably dedicate senior time to a small account. The client pays a meaningful fee for attention that doesn't match the price.
This creates a structural problem that no amount of goodwill fixes. An ads agency with fifty clients, half of them small businesses, has to prioritise. The clients spending the most get the most attention. That's rational from the agency's perspective and quietly damaging from the SME's.
Response time is another friction point. When something goes wrong in an account — a sudden spike in cost per click, a competitor outbidding you on brand terms, a campaign that's burning budget on irrelevant searches — the agency needs to be notified, needs to investigate, and needs to act. That loop takes time. In a well-run account, it should take hours. In a typical agency relationship with a smaller client, it can take days.
For businesses running ecommerce ads or time-sensitive campaigns, that lag has a direct cost.
How an AI Agent Compares to an Ads Agency
An AI agent managing Google Ads operates on a fundamentally different model. Rather than a human checking your account periodically, the agent works continuously — logging into the account, reading performance data, making bid adjustments, pausing underperforming keywords, reallocating budget toward what's working, and sending summaries of what it's done and why.
An AI agent for Google Ads is not a reporting dashboard or an automated rule set. It is an active account manager that takes actions, explains its decisions, and operates without the overhead costs built into an ads agency retainer.
The distinction from basic automation is important. Google's own smart bidding adjusts bids algorithmically. An AI agent does more: it identifies structural problems, makes campaign-level decisions, and communicates reasoning in plain language. The account receives the kind of attention that a dedicated human manager would provide, at a fraction of the cost.
Overtime is an AI agent built specifically for this. It manages Google Ads accounts for SMEs end-to-end — adjusting bids, pausing poor performers, shifting budget, and sending weekly summaries — without requiring a human manager to check in daily. For businesses whose ad spend doesn't justify an agency retainer, that's a materially different proposition.
The comparison isn't binary. An AI agent doesn't replace strategic thinking or creative judgment. What it replaces is the day-to-day account management that agencies often under-deliver on for smaller clients anyway.
For a direct comparison of these two approaches, best PPC agency or AI agent for SMEs covers the decision in more detail.
What Doesn't Work With AI-Led Management
This is worth stating plainly, because most articles on this topic won't.
An AI agent is not the right fit for every account. If your campaigns depend heavily on brand narrative, nuanced creative strategy, or complex multi-channel coordination, human oversight adds value that an AI agent won't fully cover. An agent optimises execution; it doesn't develop positioning.
Accounts in highly unusual niches — where keyword intent is ambiguous, where conversion tracking is unreliable, or where the sales cycle is long and offline — also present challenges. AI-led optimisation works best when the data signal is clean and the conversion goal is measurable.
None of that is a reason to overpay for an ads agency that checks your account twice a month. It is a reason to be honest about what your account actually needs before choosing who manages it.
For 2026, the realistic picture is that AI-led management is strong at execution and increasingly capable at structural decision-making. Human agency expertise remains more valuable at the strategic and creative layer. The best outcome for many SMEs is often neither a full agency retainer nor a set-and-forget approach, but active AI management combined with occasional strategic input.
If high cost per acquisition is already a problem in your account, that's usually an execution issue — the kind an AI agent addresses directly — rather than a strategy failure.
See Overtime's pricing if you want to understand what AI-led Google Ads management costs relative to a typical agency retainer.
Choosing Between an Ads Agency and an AI Agent
The decision comes down to three practical questions. What is your monthly ad spend? What level of strategic input do you genuinely need? And what are you currently paying for versus what you're actually receiving?
For businesses spending under £3,000 a month on Google Ads, an ads agency retainer rarely makes economic sense unless it's specifically structured for smaller accounts. The fee relative to budget is high, and the attention relative to fee is typically low.
For businesses spending above that threshold, an agency with senior account managers and a transparent fee structure can deliver genuine value — particularly if you're running campaigns across multiple channels or need creative development alongside bid management.
For the majority of SMEs in the middle — running Google Ads, wanting active management, not wanting to pay £1,500 a month for a junior account executive — an AI agent offers something the agency model has never reliably provided at accessible price points: consistent, daily account attention.
The full breakdown of what AI-led Google Ads management delivers for SMEs is worth reviewing alongside any agency proposals you receive.
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FAQ
How much does an ads agency charge to manage Google Ads?
Most ads agencies charge either a flat monthly retainer (typically £500–£2,500 for SME accounts) or a percentage of ad spend (usually 10–20%). Setup fees are common and are usually non-refundable. The fee structure alone doesn't indicate the level of active management your account will receive.
What does an ads agency actually do with your Google Ads account?
An ads agency typically handles campaign setup, keyword selection, ad copywriting, bid management, and monthly reporting. In practice, the frequency of active optimisation varies significantly by agency and account size. Smaller accounts often receive less hands-on attention than the retainer price implies.
Should an SME use an ads agency or an AI agent for Google Ads?
It depends on ad spend and what kind of input you need. If your monthly budget is under £3,000 and your campaigns are search-focused with measurable conversions, an AI agent typically provides better value than an ads agency retainer. If you need multi-channel creative strategy, a good agency adds more.
Why do some ads agencies charge a percentage of ad spend?
The percentage-of-spend model is common because it scales with client budgets and simplifies billing. The drawback is that it creates an incentive for agencies to recommend higher spend regardless of whether existing budget is being used efficiently. It's worth understanding this dynamic before agreeing to that fee structure.
Can an AI agent replace an ads agency entirely?
For day-to-day Google Ads execution — bid management, budget allocation, pausing underperformers, and performance reporting — an AI agent covers most of what an ads agency provides for smaller accounts. It does not replace strategic brand thinking, creative development, or multi-channel planning, which remain areas where experienced human judgment adds distinct value.