How do I check if a company has changed its name or number?
The short answer
Search its number, free. Search the company number on Companies House4, open the company and read its previous names. A change of name does not affect any rights or obligations2 of the company, so your invoice stands and a claim can go to the new name. The number is what marks the company out, so start from the one on your contract.
What you can add
A £3,600 invoice, 90 days late
Say you invoiced a company £3,600 on 2 June 2026, due on 2 July. In July the company changed its name. On 30 September the invoice is still unpaid: 90 days late. It went late in July 2026, so the rate is the second-half 2026 one.
Then it grows by £1.16 a day until they pay. The check cost £0. The new name changes the envelope, not the sum.
The road ahead
Four steps. All free.
Step 1: Search the number from your contract
Take the company number from your contract, quote or invoice, not from a website. Put it into the free register search5. A search by the old name usually works too, and the result shows the matching previous name.
Step 2: Read the previous names
Open the company. The page lists its previous company names4 with the period each was used, and the filing history shows when the change was filed. Companies House cannot closely review every filing1, so let the number, not the address, decide which company it is.
The registrar can also change a company's number when it adopts a new form of number. Either number counts3 for the company's trading disclosures for three years, so an old number on your paperwork can be right.
Step 3: Match the number, not the name
Same number, same company, same debt. A change of name does not affect its rights or obligations2, and proceedings that could be brought against the old name can be brought against the new one2. Interest keeps running.
A similar name with a different number is a different company. Section 216 of the Insolvency Act 19866 limits who may re-use the name of a company that failed, but that proves nothing until the numbers are checked. If they differ, search the Gazette.
Step 4: Put the current name on everything new
Keep the old invoice exactly as issued. Put the current name and number on the next invoice and every letter, and say once, in the letter below, which name the old invoice was issued to.
A letter you can copy
Email confirming the invoice and the company's current name
Send it as soon as the register shows a new name. If the date in your letter before action has passed, don't send it: start the claim against the company under its new name.
Tap a highlighted gap to see what goes in it.
Send it by email to the finance contact, so it is dated, and keep a copy with the invoice. Save the Companies House page as a PDF the same day, so you hold a record of the names and number as they stood.
When not to bother
When it isn't worth it
- You already hold the number and the name on the register matches your invoice. Nothing has changed, so stop and chase the invoice as normal.
- The customer is a sole trader. There is no register entry to read, so check the trading name and address on your own contract instead.
- The company is dissolved or in liquidation. The name no longer matters. Read about a dissolved company or one in liquidation.
- They have also gone quiet on you. A new name is a fact on a filing history, not a verdict. If other signs point to trouble, check whether the company is insolvent.
The Wolf's note
A name is a label. The number is the company. Check the number against the register, write both names on the next letter, and keep the old invoice as it was issued.
Mr. Wolf · the AI inside WolfX
What comes next
Your next move
Is this company legit? How do I check a UK company before I work for it?
Go by the company number, not the name.
5 min read · Letter included
What do "dormant", "dissolved", "in liquidation" and "proposal to strike off" mean on Companies House?
Only dissolved means a company has gone.
4 min read
How do I check if a company is insolvent or about to go under?
Three searches, ten minutes and £6: Companies House, The Gazette and the judgments register.
6 min read
Don't want to do this yourself?
The Wolf does every step for you. He works out the sums, writes the letters and keeps track of every date. Nothing goes without your yes.