Can you hire an AEO agency if you already have an SEO agency?

Yes, you can hire an AEO agency while an SEO agency is already on retainer, and running both is the normal arrangement rather than an awkward one, because the two jobs touch the site at different points. An SEO retainer is organised around the index: can the page be fetched, is it indexed, does it rank, do internal links point at it. AI visibility work is organised around a question set: which buying questions do the engines answer by naming somebody else, which pages get retrieved when they do, and what is said about you on sites you do not own.

The reason one does not simply absorb the other is measured. Mahe Chen and Nick Koudas studied 158,099 generative engine answers carrying 468,037 citations and found that which pages the engine's own search retrieves explains about 32% of the variation in citations, against 2.8% for page properties, and that the pages ChatGPT retrieves overlap little with Google's or Bing's results (arXiv 2610.15033, submitted 10 October 2026). Good Google rankings are a decent starting hand and they do not deal you into the answer.

So the practical question is not whether you are allowed two vendors. It is which one holds the pen on a page when both have an opinion about it, and who is accountable for the number each of them reports. Companies that get this wrong rarely fail on strategy. They fail because two competent teams edited the same twenty pages in the same quarter with different objectives and nobody could say afterwards which edit did what.

Settle three things before the second contract starts: who owns the publishing queue, which metrics belong to which retainer, and what each side must tell the other before touching a page. The rest of this guide is how those three decisions usually land.

Does your SEO agency already cover AI search?

Your SEO agency already covers the part that is hardest to replace, which is the technical foundation that makes a page eligible in the first place. Crawl access, indexation, server responses, internal linking and information architecture all sit inside a standard SEO scope, and all of them gate whether an engine can use the page at all.

Google's own position is blunter than most agency marketing on either side of this argument. Its guidance on AI features states that "The best practices for SEO remain relevant for AI features in Google Search", that "You don't need to create new machine readable files, AI text files, or markup to appear in these features", and that "There's also no special schema.org structured data that you need to add" (read 12 November 2026). If a vendor's pitch rests on a file or a markup trick that Google says you do not need, that is worth knowing before you sign anything.

What the SEO retainer usually does not contain is the measurement. Ask your current agency four questions and the answers will tell you quickly how much of this they really do. Which engines do they check, and how often. Can they show you the answer text and the cited sources for a buying question in your category, not a score. Who on their team owns the mentions on sites you do not control. And what would they do if the honest finding were that your pages are fine and the problem is that the model does not know your brand.

Mike King of iPullRank, which sells agency services in this category and whose conclusion therefore suits its author, puts the capacity question well: "A platform-only approach works when your team already has that expertise and capacity" (4 November 2026). The same test applies to an incumbent agency. Enthusiasm is not capacity.

Where does the work overlap, and where does it not?

The overlap is almost entirely in the technical layer, and the divergence is in what gets measured and who gets talked to. Dividing by artefact rather than by channel is what keeps two retainers from colliding, because an artefact has one owner and a channel has an argument.

Work	Usually in an SEO retainer	Usually in AI visibility work	Who should hold the pen
Crawl access, indexation, server responses	Yes	Checked, not owned	SEO agency
Information architecture and internal links	Yes	Advises on clustering	SEO agency
Keyword research	Yes	No	SEO agency
Prompt set and engine sampling	Rarely	Yes	AI visibility side
Page-level answer structure and wording	Sometimes	Yes	Whoever publishes, with one brief
Structured data and metadata	Yes	Yes	SEO agency, to one spec
Mentions on sites you do not own	Sometimes, as link building	Yes, as coverage	Split by outlet type
Reporting and attribution	Rankings and organic sessions	Citation and share of voice	Separate reports, one calendar

Two rows cause most of the trouble. Structured data gets written twice by two tools with different opinions about the same page, which produces markup that contradicts the visible copy. And mentions get chased by both, so the same trade publication hears from two agencies in one month on behalf of one client.

Fix the first with a single markup spec that both sides write against. Fix the second by splitting outlets rather than splitting effort: directories, review platforms and vendor databases on one side, editorial and analyst coverage on the other.

What breaks when two agencies work on the same pages?

The page queue breaks first, and it breaks quietly. Two vendors with publishing rights will eventually revise the same page in the same fortnight, each measuring a different outcome, and the second revision usually undoes whatever the first one was testing.

There is measured reason to care about uncoordinated rewrites rather than treating them as a project-management annoyance. SAGEO Arena, a benchmark by Sunghwan Kim, Wooseok Jeong, Serin Kim, Sangam Lee and Dongha Lee, ran optimisation strategies through a full retrieval, reranking and generation pipeline over 171,003 web documents and 2,700 queries, and reports that existing approaches "often degrade retrieval and reranking performance" (arXiv 2602.12187, submitted 12 February 2026). In its own results table, rewriting body text alone cut top-10 presence after reranking by about 16% on average across the strategies tested, while structural information in the document mitigated the damage. Read as a benchmark rather than as a verdict on your site, it still says something useful: a rewrite aimed at one stage of the pipeline can cost a page at another, so rewrites want coordination and a before-and-after reading.

The second failure is duplication. Both sides spot the same uncovered question, both commission a page for it, and now two of your pages answer one query and split whatever authority either would have had. Our guide on two pages competing for the same AI answer covers how to spot and merge that.

The third is the audit trail. When the citation count moves and three people have edited the site, the honest answer about cause is that nobody knows. A shared change log with a date, a page and a reason costs nothing and is the only thing that makes the next quarter readable.

Should you just ask your SEO agency to add AI search to the scope?

Ask your SEO agency first, because an incumbent who already owns the CMS and understands your product starts several weeks ahead of any new vendor. Expanding an existing scope is also the cheaper experiment, and if it works you have avoided a second contract entirely.

Two answers tell you it will not work. If the monthly report still leads with keyword positions and organic sessions, and the proposed addition is a slide about AI at the back, the scope change is cosmetic. And if the plan for AI visibility is a higher content volume, the plan is missing the diagnosis step. King's phrasing is the one worth quoting to an incumbent: "Publishing another article before investigating often leaves the original issue untouched" (iPullRank, 4 November 2026, from a firm that sells the alternative).

If you do expand the scope, write the addition as deliverables rather than as a channel. A named prompt set with the buying questions in it. A stated sampling cadence and the engines covered. A monthly artefact containing the engines' own answers and cited sources rather than a score on its own. A route from a finding to a page change, with whoever approves it named. And a statement of what happens to the prompt set and its history if the retainer ends.

Where the incumbent cannot staff that, the usual shape is not a second full retainer but a narrower one: somebody owns measurement and diagnosis, the SEO agency keeps the pen on the pages, and the two meet on one calendar. Our comparison of doing this in-house against a tool or an agency walks through where each model breaks down.

How do you split the budget without paying for the same work twice?

Split the budget by paying once for the pages and once for the measurement, and write the boundary into both contracts as a list of artefacts rather than as a description of a discipline. Double payment in this category almost always comes from two vendors billing for page production, not from two vendors billing for research.

What moves the total is scope rather than rate: how many buying questions you want sampled, how many engines, how often, how many pages are in scope for rewriting each month, and how much of the off-site work is bought as a service rather than done by your own communications team. A programme sampling twenty questions monthly across four engines and rewriting four pages is a different purchase from one sampling two hundred questions weekly. Our own prices are published on the pricing page rather than quoted inside guides, because a figure copied into an article goes stale the day it changes.

Three line items are worth naming explicitly when you split a budget, because each is easy to buy twice. Content production, which both vendors can do and only one should. Technical implementation, which belongs with whoever holds CMS access. And tooling, where two subscriptions tracking the same brand across the same engines will return different numbers and produce a meeting about the discrepancy rather than about the result.

What drives cost up or down in more detail, and what a cheap retainer tends to leave out, is set out in our guide to what AEO costs and what changes the quote. The budget question underneath it, which internal budget this should come from when you already fund SEO, is covered in which budget AI search visibility should come from.

How do you tell which agency moved the number?

Baseline before either agency touches anything, and keep the two kinds of metric apart on the page where you report them. A reading taken after the work started cannot be separated from the work, and a single reading cannot be separated from sampling noise.

The distinction that makes a two-vendor report readable is between an input metric and an outcome metric. Our own early results page states it plainly about our own engagements: one client's audit score moved from 17 to 68 and a second more than doubled, and that score is an input metric describing how well a site is built for citation, while share of voice is the outcome metric. A rewrite moves the first within days. Whether the engines name you more often moves on a slower clock and for reasons that include brand familiarity neither agency controls.

Then size your own noise before reading any trend. Ask the same buying question twice in an hour and the cited sources differ, which is a property of the systems rather than evidence that something changed on your site. Our guide on why AI answers change every time you ask covers the mechanism, and how to tell whether your AEO is working covers what counts as a real move across runs.

A fair split of credit usually comes out of three agreements: both vendors read the same baseline, each reports the metric it can actually influence, and any claim of causation names the page, the date of the change and the runs either side of it. If you want a neutral starting reading before either agency's work is in the data, a free visibility assessment runs your buying questions across ChatGPT, Perplexity, Google AI Overviews and Claude and shows the raw answers and cited sources.

What else do people ask about running an SEO agency and an AEO agency together?

Marketing leads running one retainer already ask these five questions most often before adding a second one.