AnswersWhen a client won't pay
Can I chase an invoice by text or WhatsApp?
The short answer
Yes, at first. A text is writing under the Interpretation Act1, the definition Acts of Parliament use: typing and any other way of showing words in a visible form. Use it for the early nudges and for getting a date. Once there is interest and a fixed sum4 to ask for, put the sums in an email, where accounts can see the working and you keep a clean copy.
England and Wales only. WolfX is software, not a law firm.
What you can add
A £2,100 invoice, paid 11 days late
Say you fitted a bathroom and invoiced another business £2,100, due Monday 14 September 2026. You text on Monday 21 September, day 7. The reply: "Paying Friday." It arrives on Friday 25 September, 11 days late. An invoice that went late in the second half of 2026 carries 8%5 over a Bank Rate of 3.75%6, so 11.75% a year.
They paid the £2,100 that day, so £77.44 is still owed on top. Ask for it in one email, with a new invoice3. Had there been no date by Monday 28 September, day 14, interest would have been £9.46, and the figures would have gone in an email that day.
The road ahead
Five steps. One stamp.
Step 1: Text with one question
Send it a week before the due date, on the due date, and again at day 7. Ask one thing: the date it will be paid. The law fixes none of these days; they are a sensible rhythm.
A read tick is not a promise and an "ok" is not a date. If the reply is not a date, ask once more for it. If they send a voice note, ask for the answer in writing.
Step 2: Keep the thread safe
Keep the chat on the phone you did the job on, and turn off disappearing messages in that chat. Screenshot with the name or number and the date and time showing, uncropped.
Use the app's export-chat option and save the copy somewhere that is not the phone. Add a line to your chase log: date, who, what was promised. Back up before you change phone.
Step 3: Email every promise back
After any promise, send one short email: "Thanks for your message on 21 September at 10:42 saying payment will be made on Friday 25 September." The promise then sits in two places.
Step 4: Move to email at day 14
No date by day 14? Work out the interest3 and the fixed sum4 and send them by email. A text can point to it: "I have emailed the figures."
The reminder email page has the words for each stage.
Step 5: Send the letter before action by email and post
Send it at day 30 if the figures email has brought no date. It sets out the claim and the sum. A company usually gets 14 days to reply2; a sole trader 30 days7. The letter is here.
A letter you can copy
Day-7 text asking for a payment date
Send it a week after the due date, from the number you normally use with them, in working hours.
Tap a highlighted gap to see what goes in it.
The subject line is for the email version. Leave it off a text or WhatsApp message. One message, one question. Do not follow it with a string of nudges, and keep threats and sharp words out of a thread that may be read later.
When not to bother
When it isn't worth it
- It has a sum and a deadline in it. Put it in an email. The letter before action goes by email and post; for a sole trader, the debt protocol says it should be sent by post7.
- They have asked for email only. Switch to email, and copy their last promise from the thread into it.
- The invoice is disputed. Settle it by a call, then write the outcome up in an email; what happens next is on its own page.
- They have ignored messages for 14 days. Another text will not help; email the finance address.
- It is a group chat, or a director's personal number. Keep the chase on the business number you used for the job, one to one.
The Wolf's note
A read tick tells you they saw it, nothing more. Ask for a date, keep the answer somewhere safer than the phone, and let the email carry the sums.
Mr. Wolf · the AI inside WolfX
What comes next
Your next move
How do I chase an overdue invoice politely?
Two short emails: on day 7, ask for a payment date; on day 14, name one, with the interest and fixed sum worked out.
5 min read · Letter included
What should a payment reminder email say at each stage?
Five emails: a week before the due date, on it, then 7, 14 and 30 days late.
6 min read · Letter included
If they push back
My client disputes my invoice. What happens next?
The disputed part waits.
6 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.