Registering a limited company at Companies House takes about fifteen minutes and £50. Undoing a formation mistake can take months and cost real money in legal fees, lost tax relief, or a corporation tax penalty you never saw coming.
Most of the damage happens in that first fifteen minutes, which is why the same ten mistakes keep landing on accountants' desks.
1. Incorporating When You Shouldn't Have
A limited company is not automatically the right structure. Below roughly £30,000 to £40,000 of profit, the admin burden and accountancy costs of a company often outweigh the tax savings, and losses in early years are easier to use against other income as a sole trader. The trade-offs are laid out in our comparison of sole trader vs limited company structures. Run that decision first; everything else on this list assumes the answer was genuinely "company".
2. Issuing One Share to One Person Without Thinking
The default one-share setup makes later changes expensive. Bringing in a spouse for dividend splitting, or an investor for growth, means share transfers with potential tax consequences instead of a clean allotment at the start. Decide who should hold equity before you file, not after the company has value.
3. Ignoring Share Classes Entirely
Alphabet shares (A shares, B shares) let a company pay different dividends to different shareholders. Set up at formation they cost nothing. Retrofitted later, they need legal work and can trigger HMRC settlement questions. Any company with two or more shareholders who aren't equal partners should at least consider them on day one.
4. Using Your Home Address for Everything
Your registered office address goes on the public record, permanently searchable by anyone. Directors put their home address on the register and then spend years fielding marketing mail and privacy worries. A registered office service costs little and keeps your home off the public file.
5. Missing the Corporation Tax Registration
Companies House tells HMRC a company exists, but you must still register for corporation tax within three months of starting to trade. New directors assume it's automatic. It isn't, and the penalties for late registration and late filing stack on top of each other.
6. Not Opening a Separate Business Bank Account
The company is a separate legal person, and its money is not your money. Trading through a personal account blurs director's loan positions, makes bookkeeping a reconstruction job, and looks terrible if HMRC ever asks questions. Open the business account before the first invoice goes out.
7. Taking Money Out Without a Method
New directors transfer cash to themselves when they need it, then discover at year end that they've built an overdrawn director's loan account with a 33.75% tax charge attached. Money leaves a company as salary, dividend, expense reimbursement or loan, each with its own paperwork, and the choice should be deliberate. Whether you need ongoing help with that is the question we answered in 7 reasons UK directors hire an accountant.
8. Forgetting the People With Significant Control Register
Every company must identify and file its PSCs, normally anyone holding over 25% of shares or voting rights. Getting it wrong is a criminal offence, not just an admin slip, and Companies House has been tightening identity verification rules for directors and PSCs. File it correctly at formation and update it when ownership changes.
9. Choosing a Name That Can't Be Used
Companies House will register a name that still infringes someone's trademark, and a "too like" objection or an infringement letter after you've printed everything is an expensive rebrand. Check the trademark register and domain availability before incorporating, not after the signage arrives.
10. Treating Formation as the Finish Line
Incorporation starts a clock: accounts due at Companies House nine months after year end, corporation tax payable at nine months and a day, confirmation statement annually, PAYE registration if you pay yourself a salary, VAT registration once turnover crosses £90,000. Directors who miss the first year's filings usually didn't know the deadlines existed. A first-year compliance calendar, set up in week one, prevents all of it.
Set It Up Right the First Time
Every mistake above is cheap to avoid at formation and expensive to fix afterwards. Company formation, share structuring and the full first-year compliance setup are part of the company formation services at ASPIRE UK, handled by ACCA-qualified accountants who also stay on for the accounts and tax side. If you're about to incorporate, or already have and recognise a few items on this list, get in touch for a free consultation before the first deadlines land.
