The verdict
You get up to nine secondary categories and most clinics use two. The right way to fill them is subtraction, not invention: list every category your competitors hold, remove the ones you already have, remove the ones you cannot honestly claim, and what is left is your shortlist. Brainstorming them in a meeting produces a list of things you wish you sold.
Nine slots. On most of the profiles I audit, two are filled and seven are empty, and the two were chosen at setup by the same person who chose the primary in the same ninety seconds.
Empty slots are not neutral. They are relevance you are not claiming for services you actually provide.
Why subtraction beats invention
Ask a practice owner to list their secondary categories and you get an aspirational list. Things they are trained in but rarely do. Things they would like more of. Things that sound impressive.
Build it from the competitor set instead and you get an empirical list. I collect the primary and all secondary categories for eight to ten competitors in the same market, put them in a single sheet, and look at what appears repeatedly that the client does not hold. Anything three or more competitors carry is table stakes. Anything one competitor carries is an opportunity or a mistake, and you have to decide which.
The sheet takes an hour and it replaces an argument with a list.
The filter that stops the list getting silly
That second test does most of the work. A clinic that has a massage therapist is not a massage business. A practice that has an X-ray machine is not a radiology service. Run every candidate through IS a and the aspirational half falls out immediately.
The guidance also notes that when you select a specific category, Google automatically understands the related general ones, so you do not need to claim both the specific and the broad version. That frees up slots people routinely waste.
My note: “as few as possible” and “you have nine slots” are in tension, and I resolve it in favour of accuracy. Nine accurate categories is fine. Four accurate ones and five stretches is worse than four. The instruction is about not padding, not about leaving relevance unclaimed.
What a wrong secondary actually costs
Not a penalty. Calls.
A category you cannot properly serve generates enquiries you have to decline, and each of those costs a receptionist five minutes and a caller their goodwill. That cost is invisible because nobody logs it. It is real, and it is the reason I would rather leave a slot empty than fill it defensively.
This matters more in health than in trades. Somebody who rings a roofer about guttering and gets told no has lost nothing. Somebody who rings a clinic about a condition you do not treat has been told, in effect, that your profile said you did.
How this connects to the rest
Categories set relevance, and Google names relevance as one of the three things behind local results, alongside distance and prominence. Getting nine of them right is the cheapest relevance work available to a local business and it is done once.
It comes second in the eight-check order I run on every Business Profile, right after benchmarking your primary category against the map pack, and for the same reason: the answer is sitting in public on your competitors’ profiles.
The short version
- Nine slots, and most clinics use two. Empty slots are unclaimed relevance.
- Build the list by subtraction from competitors, not by brainstorming in a meeting.
- Three or more competitors hold it, it is table stakes. One holds it, decide if it is an opportunity or their mistake.
- Run every candidate through the IS a test. It removes the aspirational half instantly.
- A specific category implies the general one. Do not spend two slots saying one thing.
- A wrong secondary costs calls, not rankings. Invisible, real, and worse in health than in trades.
- Do it once, properly, after the primary.
If a site should be ranking and it isn’t, that’s the work I do. SEO for chiropractors covers where the effort belongs in a practice, and an SEO audit is where the competitor category sheet gets built for your market.
