How to name a
UK limited company.

A private limited company's registered name must end with “Limited” or “Ltd”. Register in Wales and you may use “Cyfyngedig” or “Cyf” instead. The ending is part of the name, not decoration on it.

There is an exception, and it is narrower than people hope: a company that is a registered charity or is limited by guarantee can be exempt from the ending, provided its articles of association meet specific conditions about not distributing to members. If that is not you, the ending applies.

Your name cannot be the same as one already on the register. What catches people is how wide “same as” reaches: a name counts as the same when the only difference is punctuation, a special character, or a word or character that is similar in appearance or meaning to one in the existing name.

So “Hartwell & Co Limited” and “Hartwell and Company Ltd” are not two names to Companies House. Nor are “Kestrel-Hire” and “Kestrel Hire”. Choosing a name by adding a hyphen to one that is taken does not work, and finding that out at filing is the common way to discover it.

You can register a “same as” name in one situation: your company is part of the same group as the existing company or LLP, and you have written confirmation that they do not object.

This is the rule that surprises people most, because it operates after you have registered rather than before. If your name is too similar to an existing company's name or trade mark, someone can complain — and if Companies House agrees it is “too like” a name registered before yours, you can be directed to change it.

Nothing stops the registration at the time. You can incorporate, print stationery, buy the domain and launch, and still be told to change the name because a company registered in 2011 has objected. Which is why the sensible order is to search the register and the trade mark database before you file, not after.

A name cannot contain a “sensitive” word or expression, and cannot suggest a connection with government or a local authority, unless you get permission first. The list covers words implying pre-eminence or authority — the sort of thing that makes a two-person company sound like a national institution — as well as regulated activities and professions.

Permission is not a formality but it is not a wall either: some words need the written view of a specified body, which you then submit with the application. If a word on your shortlist feels like it is claiming something, check it before you get attached to it.

Separately and absolutely: the name cannot be offensive.

A company name can be up to 160 permitted characters. Permitted means A–Z, 0–9, and this set of symbols: & @ £ $ € ¥ #, plus the full stop, comma, colon, semi-colon and hyphen.

The trap is in how they are treated. Punctuation can be used, but it is ignored when availability is checked — so it can never be the thing that makes your name different from one already registered. Use a symbol because it belongs in the name, never because it clears a collision.

If you trade under something other than your registered name, that trading name has its own constraints. It may not include “limited”, “Ltd”, “limited liability partnership”, “LLP”, “public limited company” or “plc” — those endings say something specific about liability, and using one you do not hold is a misrepresentation rather than a style choice.

Sensitive words apply here too. And a trading name is registered nowhere, which is the important thing to understand about it: it gives you no protection by itself. Protection comes from a trade mark.

Companies House accepting your company name tells you nothing about trade marks. They are different registers with different tests, run by different bodies, and a name can be perfectly registrable as a company while infringing a mark someone else owns in your class of goods or services.

Search the UK Intellectual Property Office's trade mark database for your shortlist before you commit. If the brand matters — if it is going on packaging, or into a category with well-funded incumbents — get advice on registering your own.

Of the three checks, the domain is the only one that answers instantly and unambiguously, and it is the one most likely to eliminate a name. Run it first and you will not spend an afternoon on a name that was never available.

It is also first-come, first-served in a way the others are not: there is no complaints process and no “too like”. If it is gone, it is gone, or it is for sale at whatever the holder asks.