AnswersWhen a client won't pay
Can I see whether a client has opened my invoice?
The short answer
Sometimes. Invoicing software can show that a link or image in your email was fetched, but not who by, or whether anyone read it. The late payment law1 does not ask whether an invoice was opened: an agreed payment date is the date, opened or not. If none was agreed, the 30 days start when the customer gets the invoice, or when the work is delivered if that is later2.
What you can add
A £9,000 invoice the client says they missed
Say a recruiter emailed a £9,000 invoice on Monday 3 August 2026, on 30 days from the invoice date, so due on Wednesday 2 September. The tracker showed it opened on 4 August. On 14 September the client said they had not seen it. They paid on 30 September: 28 days late. It went late on 3 September, so the yearly interest rate is 11.75%5.
The tracker changed none of it. The date was agreed, so interest ran from 3 September whether or not anyone opened the email. What would have shown they had it: the sent email with no bounce, their reply quoting the invoice number, and their payment confirmation.
The road ahead
Four steps. All free.
Step 1: Find your date
If you agreed a payment date, that date is the one1, whether or not anyone opened the invoice. If you agreed none, the 30 days start when the customer gets the invoice2, or when the work is delivered, if that is later.
The Act's own words are that the purchaser "has notice of the amount of the debt" (section 41). Neither it nor GOV.UK says opened or read.
Step 2: Ask for a receipt in words
Email the note below a week before the due date, or on the due date at the latest. The law sets no day for this note, but a week leaves time to resend an invoice that went astray. It asks one thing: confirm you have the invoice and say when it will be paid. You usually get a one-line reply, and that is worth more than any tick.
Step 3: Keep what shows they have it
File the sent email with no bounce, any reply that quotes your invoice number or their order number, an upload receipt from their portal, and the other side's payment confirmation when it comes.
Court papers are different. For a claim, the Civil Procedure Rules give deemed service times for email6, and require the other side to have said in writing that they accept email7. Neither is a rule for invoices.
Step 4: Treat "viewed" as a prompt to ring
If your software shows the invoice was viewed or a link was clicked, ring on day 7 and ask when it will be paid. Do not tell them you can see they opened it. It proves little, and it reads as a threat.
Tracking also touches privacy law. Regulation 6 of the Privacy and Electronic Communications (EC Directive) Regulations 20038 says a person "must not store information, or gain access to information stored, in the terminal equipment of a subscriber or user", subject to Schedule A1. A data protection solicitor can say whether your tool falls inside it.
A letter you can copy
Email asking them to confirm they have it
Send it a week before the due date, or on the due date at the latest.
Tap a highlighted gap to see what goes in it.
Send it as a reply on the original invoice email, so the thread shows the number and the date. Keep their answer with the invoice, in your log.
When not to bother
When it isn't worth it
- The date is more than a week away. Nothing is late, so a tracker has nothing to tell you. A week before the date, send the email to check they have it.
- They have already replied. You know they have it. Ask when it will be paid.
- You already chase on a fixed rhythm. Reminders on day 7, 14 and 30 go out whatever a tick says, so the tracker adds nothing.
The Wolf's note
A tick that says opened tells you something was fetched. It does not tell you who read it, and the due date does not wait for it. A reply in words settles the question, so ask for one and file it with the invoice.
Mr. Wolf · the AI inside WolfX
What comes next
Your next move
My client says they never received my invoice. What do I do?
Resend the same invoice today, to two places, and ask for a reply.
5 min read · Letter included
When is an invoice officially late?
An invoice is late the day after the agreed date.
5 min read · Letter included
What do "pending approval" and "it's in the payment run" really mean?
Neither is a payment date.
5 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.