Most small businesses that hire paid search agencies discover the same thing within six months: the account manager handling their Google Ads is also handling fourteen other accounts, and the monthly report tells them very little about what actually changed or why.
This article explains what paid search agencies actually do, what they cost, where they fall short for smaller budgets, and what the alternative looks like in 2026 — including how an AI agent can replicate most of what an agency does, at a fraction of the cost.
What Paid Search Agencies Actually Do
A paid search agency manages Google Ads (and sometimes Bing or other paid channels) on behalf of clients. In practice, that means keyword research, campaign structure, bid management, ad copy, audience targeting, and monthly reporting. The better agencies also handle landing page recommendations, conversion tracking, and budget allocation across campaigns.
The definition worth having clearly stated: a paid search agency is a specialist firm that manages pay-per-click advertising campaigns on behalf of clients, typically charging a monthly management fee, a percentage of ad spend, or a combination of both.
What agencies rarely advertise is how much of this work is reactive rather than proactive. Bids get reviewed when something breaks or when a client complains. Budgets get reallocated at the end of the month rather than in real time. The account gets attention when it earns attention — and with a junior exec managing a large portfolio, that often means your account sits untouched for stretches of two or three weeks.
That is not a criticism of the people involved. It is a structural problem. After nine years running a marketing agency, we saw this pattern repeatedly: the work that genuinely moves performance is the daily, unglamorous stuff — checking search term reports, pausing irrelevant keywords, nudging bids on campaigns that are just short of a profitable cost-per-acquisition. That work is hard to bill for and easy to defer.
If you want to understand what a paid search management service actually delivers in practice, it is worth reading beyond the pitch deck.
What Paid Search Agencies Typically Charge
Pricing varies significantly, but there are three common models used by paid search agencies.
| Pricing Model | Typical Cost | Best For |
|---|---|---|
| Flat monthly retainer | £500–£3,000/month | SMEs with consistent spend |
| % of ad spend | 10–20% of monthly budget | Higher-spend accounts (£5k+/month) |
| Hybrid (retainer + %) | £300–£1,000 + 8–15% | Mid-sized accounts |
| Performance-based | Rare; often % of revenue | E-commerce, lead gen |
For businesses spending less than £3,000 per month on Google Ads, the economics rarely work in their favour. A 15% management fee on a £2,000 budget is £300 — not enough to justify a senior practitioner's time, which means the account gets assigned to someone junior. If you are curious about how much Google Ads actually costs for SMEs, the spend threshold matters more than most agencies acknowledge upfront.
The minimum viable budget where an agency relationship genuinely pays off is probably around £5,000 to £8,000 per month in ad spend. Below that, you are often paying management fees for work that does not keep pace with how fast the Google Ads auction actually moves.
How Paid Search Agencies Manage Google Ads Accounts
The operational reality of agency-side Google Ads management is worth understanding before signing a contract. Most agencies use a combination of Google Ads scripts, third-party bid management tools, and manual account reviews. The frequency of those reviews depends on the account tier — which usually means how much you spend.
A standard workflow at a mid-sized paid search agency might look like this: onboarding takes two to four weeks, campaign build takes another two to four weeks, and meaningful optimisation data takes ninety days to accumulate. You are looking at four to five months before the relationship is genuinely humming. That is not unreasonable — Google Ads does require a learning period — but it means the first quarter of fees often buys setup rather than results.
Day-to-day bid management is where the gap between promise and delivery tends to open up. Google's Smart Bidding handles a lot automatically now, but it still requires human oversight to catch anomalies: a competitor starts bidding aggressively on your brand terms, a product goes out of stock but the campaign keeps running, a new search term starts converting at three times your target CPA. These are the moments where active management earns its fee. For context on how brand bidding in Google Ads can affect your costs, it is an area that benefits from daily monitoring rather than weekly check-ins.
See how an AI agent handles this kind of active monitoring
Where Paid Search Agencies Fall Short for Smaller Budgets
This is where we will say something that would not appear in a generic overview of the industry: paid search agencies are structurally misaligned with SME interests.
The agency model rewards client acquisition and retention. It does not automatically reward account performance. An agency keeps your contract by maintaining a relationship with you — by being responsive, producing reports, and appearing competent. Whether your cost-per-click is 8% lower this month than last month is a secondary concern unless you are tracking it closely yourself.
This is not cynicism. It is how service businesses work. The incentive to do the painstaking, time-consuming work of shaving waste out of your account is low when that work does not directly protect the contract. We saw this from the inside for nearly a decade, and it is the reason so many SMEs churn through paid search agencies without ever seeing the results they were promised.
The specific failure modes tend to be: broad match keywords left running without negative keyword lists, ad groups with three or four ads where the worst performer is never paused, and budgets that roll over at the end of the month without any intra-month reallocation. None of these are dramatic failures. Together, they represent 20 to 30% waste on an average account. Understanding how to fix high cost per acquisition in Google Ads often comes down to catching exactly these kinds of slow leaks.
Paid Search Agencies vs AI Agents: A Direct Comparison
The question SMEs are increasingly asking is not "which paid search agency should I use?" but "do I need a paid search agency at all?"
An AI agent approaches Google Ads management differently. Rather than reviewing an account weekly or fortnightly, it operates continuously — logging in, checking performance, adjusting bids, pausing underperforming ads, and reallocating budget based on live data. It then sends plain-English summaries so the business owner knows exactly what changed and why.
View Overtime's pricing and what's included
Overtime is an AI agent built specifically for this. It connects to your Google Ads account, makes bid and budget decisions autonomously, and surfaces the kind of account hygiene issues that tend to get missed in a weekly agency review cycle. The difference is not just speed — it is consistency. The account gets looked at every day, not when the account manager has a gap in their calendar.
For businesses spending between £500 and £5,000 per month on paid search, this model is worth serious consideration. The management overhead is lower, the response time to account changes is faster, and the cost is typically a fraction of a traditional agency retainer. If you want a grounded comparison of the two approaches, the article on whether a PPC agency or AI agent is the right fit for SMEs goes into the decision criteria in detail.
The trade-off is worth naming honestly: an AI agent does not replace a strategist. If you need someone to rethink your campaign architecture from scratch, write new ad copy, or consult on whether paid search is the right channel for your business, that requires human judgement. An AI agent is excellent at execution. It is not the same as having a senior paid search strategist on retainer.
What it does replace, accurately, is the junior account management layer that most SMEs are actually paying for when they hire a paid search agency at the lower end of the market.
For a fuller picture of the service landscape, the guide on what PPC agency services actually include is useful context before making any decision.
Making the Decision: Agency, AI Agent, or Both
For most SMEs in 2026, the honest answer is that paid search agencies make sense above a certain spend threshold and a certain complexity threshold — and below those thresholds, the maths does not work in your favour.
If you are spending less than £5,000 per month on Google Ads, running straightforward search campaigns, and do not have the internal resource to manage the account yourself, an AI agent will almost certainly outperform the level of service you would actually receive from a paid search agency at that budget. Not because agencies are bad, but because the economics mean you are not getting their best people or their most attentive service.
If you are spending more than that, running multi-channel campaigns, or operating in a highly competitive sector where strategy matters as much as execution, a specialist agency with strong credentials may well be worth the investment — particularly if you can verify their track record with accounts similar to yours in size and sector. Google's own guidance on working with Google Ads partners is a reasonable starting point for evaluating agency credentials.
The middle path — using an AI agent for day-to-day execution while retaining occasional strategic input from a freelance consultant — is increasingly common and often the most cost-effective structure for growing businesses. For businesses in specific markets, resources like the guide on what a PPC service actually delivers for SMEs can help frame what you should expect regardless of who manages the account.
If you are currently paying a paid search agency and not seeing clear evidence of proactive account management — daily bid adjustments, regular negative keyword additions, budget reallocation based on performance — that is worth addressing directly. See what Overtime does inside a Google Ads account and compare it against what your current setup is actually delivering.
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FAQ
What do paid search agencies charge for Google Ads management?
Paid search agencies typically charge either a flat monthly retainer (usually £500 to £3,000 for SME accounts), a percentage of ad spend (commonly 10 to 20%), or a hybrid of both. For accounts spending less than £3,000 per month on ads, management fees can represent a disproportionately high share of total spend.
How do paid search agencies manage Google Ads accounts on a day-to-day basis?
Most agencies use a combination of automated bidding, Google Ads scripts, and scheduled manual reviews. The frequency of hands-on attention typically depends on how much a client spends — higher-spend accounts receive more regular management. For smaller budgets, reviews are often weekly or fortnightly rather than daily.
What should I look for when evaluating paid search agencies?
Ask specifically how often the account is reviewed, who will manage it (not just who pitches the work), and what their process is for catching and pausing underperforming keywords or ads. Agencies that cannot give clear, specific answers to those questions are likely relying heavily on Google's automated systems without much active oversight.
Should I use a paid search agency or an AI agent for Google Ads?
For businesses spending under £5,000 per month on Google Ads, an AI agent typically delivers more consistent active management than the level of service available from agencies at that budget. Above that threshold, with complex campaigns or multiple channels, a specialist agency may offer additional strategic value that justifies the higher cost.
Can an AI agent replace everything a paid search agency does?
Not entirely. An AI agent handles execution well — bid management, budget reallocation, pausing underperformers, and account monitoring. It does not replace strategic thinking, creative ad copy development, or channel planning. For most SMEs, however, execution is the gap that matters most and the area where agency service most often falls short.