My client says my invoice came too late to be valid. Is that true?
The short answer
No. No law makes a late invoice void, and you have six years8 to claim what you're owed. A late invoice moves one date: if no payment day was agreed, the 30 days to pay run from when the client has your invoice1, so interest starts later, but it still starts. A real deadline would be a term in a contract, so read yours and theirs.
England and Wales only. WolfX is software, not a law firm.
What you can add
A £4,200 invoice sent 88 days after the work
Say you finished a £4,200 report for another business on 5 March 2026 and invoiced on 1 June 2026. No payment day was agreed, so their 30 days run from 1 June to 30 June, and interest starts on 1 July. On 14 August 2026 it is still unpaid: 45 days late.
Then it grows by £1.35 a day until they pay. Had you invoiced on 5 March, interest would have started on 4 April. The late invoice cost you those 88 days, £118.98 at the same rate. The debt itself is untouched.
The road ahead
Four steps. All free.
Step 1: Look for a time limit in writing
Read your contract, your quote and their purchase order for wording on when invoices must be sent, such as "invoice within 90 days". If both sides agreed that term, it can count. Their budget year or month-end cut-off is not law. If no price was fixed, the client owes a reasonable charge9.
Step 2: Date the invoice the day you send it
Do not backdate it. Put the day the work was finished on the invoice or in the email, and attach the proof of the work.
If you are VAT-registered, HMRC's guide says to normally issue a VAT invoice within 30 days of the tax point10, with listed cases that extend it. That is a rule about your VAT paperwork. The guide does not make it a time limit on being paid.
Step 3: Work out when interest starts
With an agreed payment day, interest starts the day after it. Without one, the 30 days begin on the later of the day the work was done and the day they had notice of the amount7, and interest starts the day after they end. See when an invoice is late for the count.
Step 4: Reply in writing and ask for a date
Send the letter below. It asks them to point to any clause they rely on, and gives them 14 days to pay or reply. If they dispute the work itself, read what happens when a client disputes an invoice.
A letter you can copy
Reply to "your invoice is too late"
Send it once the client has said the invoice came too late, before you reply by phone or argue the point.
Tap a highlighted gap to see what goes in it.
Send it by email so it is dated, with a copy of the invoice and your proof of the work attached. If you have no agreed payment day and the invoice went out late, count the 30 days from the day the client had it, not from the day of the work.
When not to bother
When it isn't worth it
- Your own contract has a time limit and you missed it. An agreed term is the real risk. Ask whether they will waive it and weigh the sum; on a large one, a solicitor who does debt recovery can tell you whether the clause binds you.
- They are really disputing the work. A late invoice can be the first excuse to hand. Settle the undisputed part and read what happens next.
- The work is close to six years old. With no agreed payment day, count the six years8 from the day you finished the work, not the invoice date. Check the date now.
- Your client is a consumer. The interest rules only cover sales between businesses6, and consumer debts need a different page.
- You are in Scotland or Northern Ireland. The six years is the England and Wales rule in section 5 of the Limitation Act 19808, so check the time limit where you are.
The Wolf's note
A late invoice is slow, not void. The law gives you six years to claim, so the only deadline worth hunting for is one somebody signed. Find the clause, or find there isn't one, then ask for a date.
Mr. Wolf · the AI inside WolfX
What comes next
Your next move
When it first goes quiet
When is an invoice officially late?
An invoice is late the day after the agreed date.
5 min read · Letter included
My client disputes my invoice. What happens next?
The disputed part waits.
6 min read · Letter included
What you can add
Can I charge interest on a late invoice?
Yes, if you sold to another business.
3 min read · Letter included
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.