The short version: Every small business using AI to write content ends up with the same flat, slightly cheerful, faintly American tone, because the tools were trained on the same internet everyone else’s tool was trained on. The fix isn’t a better prompt. It’s a one-page document you build once, feed to every tool you use, and update every quarter, built from your own words, your customers’ words, and the phrases you’d never be caught dead saying.
The problem nobody wants to say out loud
I read a lot of small business content for a living. Newsletters, LinkedIn posts, About pages, product descriptions. And since early 2024 I can spot AI-written copy in about four seconds, not because it’s badly written, but because it’s suspiciously well written in a way that has no fingerprints on it. “In today’s fast-paced world.” “Whether you’re a seasoned professional or just starting out.” “Let’s dive into.” Every business selling completely different things starts sounding like the same slightly enthusiastic colleague.
Here’s the bit most people skip past because it’s uncomfortable: your AI tool isn’t the problem. You are. ChatGPT, Claude, Gemini, whatever you’re using, they’re all trained on roughly the same corpus of internet writing, which means their default voice is a kind of statistical average of every blog, every LinkedIn thought-leader post, every SaaS homepage ever indexed. If you give it a two-line prompt and hit generate, you get the average. That’s not the tool failing you. That’s the tool doing exactly what you asked.
The businesses whose AI content doesn’t sound generic aren’t using secret prompts. I’ve asked several of them what they do differently and it’s almost always the same answer: they fed the model pages and pages of their own real writing first. Not instructions about their voice. Actual examples of it.
What a brand voice document is (and isn’t)
A brand voice document is not a mood board with three adjectives on it like “friendly, professional, innovative.” I’ve seen dozens of these and they’re useless, because “friendly” means something different to a funeral director and a nightclub. What you need instead is a working document, four to six pages, built from real material, that any AI tool (or freelance writer) can read and immediately sound more like you.
Look at how differently four brands with distinct voices write. Duolingo’s marketing strategy leans on chaos and self-deprecating humour, an owl that will “ruin your life” if you skip a lesson. Calm’s marketing strategy does almost the opposite, short sentences, lots of white space, nothing urgent, ever. Hotjar’s marketing strategy talks to marketers like a slightly blunt colleague who’s read the data and doesn’t have time to dress it up. Revolut’s marketing strategy is confident bordering on cocky, short punchy claims, numbers up front. None of those voices came from a prompt. They came from a person or a small team deciding, on purpose, what they would never sound like, and writing that down.
The document, section by section
This is the structure I use with clients now, and the one I finally sat down and wrote for my own business last year after getting fed up with my own AI-drafted newsletters sounding like nobody I’d ever met.
- Ten real sentences you’ve written that sound like you, pulled from old emails, voice notes transcribed, or a call recording. Not polished marketing copy, raw stuff.
- Five phrases you would never say, and this list matters more than the first one. Mine includes “unlock your potential,” “in today’s fast-paced world,” and “let’s dive in.” Every AI tool defaults to these. Naming them as banned is the single fastest way to stop seeing them.
- Three things your customers say about you, taken word for word from reviews, DMs, or testimonials. Not the polished testimonial you’d put on a landing page, the throwaway line in the middle of it. A client of mine, a bookkeeper in Leeds, had a review that said “she just gets on with it, no faff.” That phrase, “no faff,” became the backbone of her entire voice document. No AI tool would have invented it. Her customer did.
- One sentence describing your rhythm: short and punchy, or long and considered? Do you use contractions? Do you ever swear, even mildly? Do you write in second person (“you”) or first (“I” or “we”)?
- Three competitors or well-known brands you sound nothing like, and one line on why. This works the same way the banned-phrases list does, it’s often easier to define yourself against something than to describe yourself in a vacuum.
- A worked example: take one piece of AI-generated content you weren’t happy with, and rewrite the first three paragraphs in your real voice, side by side. This becomes the single most useful reference in the whole document because it shows the model an actual before and after, not just a description.
That’s the whole thing. Four to six pages, built in one sitting if you’re organised, or across a slow Sunday if you’re not. The unglamorous part is that nobody can build this for you in twenty minutes. I’ve tried shortcuts, asking a client to fill in a quick form, and it never works as well as sitting with them for ninety minutes and pulling real sentences out of their old emails while they talk.
How to use it
Once it exists, paste the whole document into your AI tool at the start of every session, before you ask it to write anything. In ChatGPT or Claude you can save it as a custom instruction or project file so it’s always loaded. In Gemini you can pin it to a saved conversation. The step people skip is re-pasting it, they write the document once, use it for a week, then go back to bare prompts because it’s an extra thirty seconds of friction. That thirty seconds is the whole difference between content that sounds like you and content that sounds like the average of the internet.
I test new drafts against a simple rule now: if I could delete the company name and the text would work for a competitor, it’s not done yet. That single check has killed more of my own AI drafts than any other filter.
A UK accountancy firm I worked with in 2024 ran this test on six months of their existing blog content and found that four out of five posts passed the “swap the logo” test, meaning they read as generic finance advice that any accountant in the country could have published. After building the voice document (their standout phrase, taken from a client review, was “he rings you back,” which became the seed for a whole tone built around reliability over cleverness) their next batch of posts dropped to one in five failing the test. Same AI tool. Same writer. Different input.
Where this connects to bigger business skills
None of this is really about AI. It’s about the old-fashioned skill of listening to how people talk about you, which is more or less what Dale Carnegie was banging on about nearly a century ago. A lot of the business lessons from Dale Carnegie boil down to one idea: people respond to being heard in their own language, not yours. A voice document is that principle turned into a working file you can hand to a machine.
It also pairs well with anything on your site that invites people to type their own words in. If you’ve got an interactive calculator or a quiz collecting open text answers, that’s one of the richest sources of real customer phrasing you’ll ever get, because people write differently into a form than they do in a polished review, and that rawer language is exactly the material your voice document is short on.
The quarterly update most people forget
Your voice document goes stale. New customer phrases show up, you drop old ones, your own writing style shifts as your business matures (mine got noticeably shorter and blunter over the five years I spent rebuilding after 2020, and my voice document from that period is nothing like the one I use now). Set a recurring reminder every three months to add one new real sentence, one new banned phrase, and one new customer quote. Ten minutes, four times a year. Skip it and you’ll be back to sounding like everyone else by Christmas.
Frequently asked questions
Do I need a different voice document for LinkedIn versus my website?
No, one document covers both, but add a short note on formatting differences, shorter sentences and more line breaks for LinkedIn, fuller paragraphs for your website. The underlying voice, the phrases, the rhythm, the banned words, stays the same across every channel.
Can I just ask ChatGPT to “sound more human”?
You can, and it will change slightly, but it’s still guessing at an average of “human,” not writing like you specifically. The instruction “sound more human” produces a different flavour of generic. Feeding it your actual sentences and your customers’ actual words is what produces something that sounds like your business rather than a business.
How long should a brand voice document be?
Four to six pages is enough for a small business. Longer than that and nobody, including you, will re-paste it before every writing session, which defeats the purpose. Short, specific, and used beats long and ignored every time.
Is this worth paying someone to build for me?
If you’ve tried it twice and your content still reads generic, yes, it’s usually a half-day of focused work with someone who knows what to pull out of your old emails and reviews. It’s one of the first things I build with clients now when I work through AI consulting for small businesses, because it makes every piece of AI content afterwards faster to produce and less embarrassing to publish.
If you want the full breakdown, here is everything I know about AI marketing.
Related reading: Best Free Digital Business Card Apps: What I’d Download in 2026 and AI News This Week for Small Business, 19 July 2026.
