Why the reminder that matters goes before the due date#
Many payables teams pay in batches on set days, and an invoice joins a batch only after it is matched to a PO and approved by the budget owner. If any of that is missing on day 25 of 30, the invoice misses the batch, and nobody tells you. You find out on day 31, and the fix then takes another cycle.
A reminder before the due date surfaces the problem while there is still time to fix it: an invoice in the wrong inbox, a PO that expired, an approver on leave. A client who gets a polite check on day two and a short note on day 23 rarely sees it as pressure. It reads as a supplier who is organized.
An example, used in the letters below. A QA firm sends invoice INV-2026-031 for $9,800, the October testing under SOW 2, on Tuesday, October 20, 2026, net 30. It is due Thursday, November 19.
| What | Send on | Purpose |
|---|---|---|
| 1. Receipt check | Thu, Oct 22 or Fri, Oct 23 | Confirm it is logged against the PO |
| 2. Week-before note | Thu, Nov 12 | Confirm it is approved for the next run |
| 3. Due-date line | Thu, Nov 19 | The link, one sentence |
Letter 1: the receipt check, two or three business days after the invoice#
This one asks a question AP can answer in a minute. It catches the most common cause of a late payment early: the invoice never got into their system.
Payment reminder 1: did the invoice arrive?
To the AP inbox, your contact in Cc. Two or three business days after the invoice. Attach the invoice PDF.
Hello,
We sent invoice [INV-2026-031] for [$9,800] on [October 20] for [the October testing under SOW 2]. It is due on [November 19], against PO [4500123].
Could you confirm it is in your system and matched to the PO? If anything is missing for your process, an approver's name or a different entity, tell me and I will send a corrected copy today.
The PDF is attached again, and you can pay by bank transfer or here: [payment link].
Thank you,
[Your name], [Your firm]
If they use a supplier portal, the receipt check is your own: log in, find the invoice, and read its status. Write to AP only if it shows “rejected” or “on hold”, and quote the reason the portal gives.
Letter 2: the friendly reminder, a week before the due date#
Seven days is enough to fix an approval and still make a weekly batch. The letter names the date and asks one thing: is it approved?
Payment reminder 2: a week before the due date
To the AP inbox, your contact in Cc. Seven days before the due date. Attach the invoice PDF.
Hello,
A short note that invoice [INV-2026-031] for [$9,800], PO [4500123], is due on [Thursday, November 19].
Is it approved for your payment run before that date? If it is waiting on an approval, [contact's name] in Cc can help.
Payment link: [payment link]. The PDF is attached.
Thank you,
[Your name]
To your contact, not AP, when the client has no shared inbox and your contact approves the invoice:
Payment reminder 2, to the person who approves
To your contact. Use it when the invoice waits on their approval, not on AP.
Hi [Name],
Invoice [INV-2026-031] for [the October testing] is due on [November 19]. If it is waiting on your approval in [their system], could you approve it this week, so it makes the next run?
The timesheet you approved on [date] is attached, with the invoice.
Thanks, and see you at [the next project meeting].
[Your name]
Letter 3: on the due date, one line and the link#
On the day, say less. The link does the work.
Payment reminder 3: due today
To the AP inbox. On the due date, in the morning of their time zone. No attachment needed; the link is enough.
Hello,
Invoice [INV-2026-031] for [$9,800], PO [4500123], is due today. You can pay it here: [payment link].
If it has already gone out, thank you, and please ignore this note.
[Your name]
If the payment arrives on the due date, send nothing more. If it does not, the next letter is the first overdue one, three days later: the overdue invoice email has it, with the versions for 10 and 30 days.
The whole payment reminder sequence, before and after the due date#
A payment reminder email is one letter in a sequence. Most firms send three before the due date and three after it, and stop when the money arrives. Plan the dates the day you send the invoice, so no reminder depends on someone remembering it.
| What | The payment reminder | Where the template is |
|---|---|---|
| 2 or 3 business days after the invoice | Receipt check | Letter 1 on this page |
| 7 days before the due date | Friendly reminder | Letter 2 on this page |
| On the due date | Due date reminder, one line and the payment link | Letter 3 on this page |
| 3 days late | First overdue payment reminder: did something block it? | The overdue invoice email |
| 10 days late | A firmer note to AP and your contact, with the outstanding balance | The overdue invoice email |
| 30 days late | Final notice: one date to pay by, one step the contract allows | The final notice |
The letters after the due date change in tone, not in content: the same invoice number, PO, amount and payment link, a little firmer each time. They are on two pages of their own: the overdue invoice email, for 3, 10 and 30 days late, and the final notice, for the last letter. Late fees belong in a reminder only when your contract has them; the late payment fee clause shows the wording. If a client asks for time, a short payment plan in writing beats a fourth reminder: how to ask a client for payment has the call.
The email when the payment arrives#
Close the loop. A two-line payment confirmation tells the client the matter is done and keeps the next invoice welcome.
Payment received: thank you
To your contact, with AP in Cc. The day the payment shows in your account.
Hi [first name],
We received payment of [$9,800] for invoice [INV-2026-031] today. Thank you, and please pass our thanks to your payables team.
The next invoice under SOW [3] is [the November retainer], due [date]. I will send it on [date].
[Your name]
Payment reminder subject lines that get read and filed#
An AP clerk sorts by invoice number. A subject line with the number, the PO and the date gets matched without opening the email. A subject line that says “Quick question” gets opened last.
Invoice [number] for PO [number] received?
Invoice [number] due [date]
Due today: invoice [number], [amount]
[Your firm] invoice [number]: approval before [date]
Invoice [number], [project], [month] timesheet attached
Avoid “Friendly reminder” alone, “Following up” and “Just checking in”. They tell the reader nothing they can file.
What every payment reminder should carry#
| What | Why their AP needs it |
|---|---|
| Invoice number | Their system finds invoices by number |
| PO number | The invoice is matched to the PO before it is paid |
| Amount and currency | To check against the PO balance |
| Due date, as a date | "Net 30" alone makes the clerk count |
| What it is for: the SOW, the milestone or the month | So the approver recognizes the work |
| The invoice PDF, attached again | The first copy may be in someone else's inbox |
| A payment link, and your bank details as registered | One click, or the transfer they already set up |
| Your contact in Cc | They can unblock an approval |
| For hourly work, the approved timesheet | The approver checks hours before money |
Send the reminder in the thread of the original invoice email when you can. The clerk then sees the invoice and the reminder together.
Variants for milestone, retainer and hourly invoices#
A milestone invoice. Name the acceptance in the first line: “Invoice [number] covers [milestone], which [name] accepted on [date].” An approver who sees the acceptance does not need to ask the project team.
A retainer. Name the month and the fixed amount: “Invoice [number] is the [November] retainer of [$12,000], per SOW [3].” Retainer invoices look alike; the month is what tells them apart.
Hourly work. Attach the timesheet the client approved, and say when: “The hours match the timesheet [name] approved on [date].” It answers the question before the approver asks it.
Set up payment reminder emails in Tommos#
Tommos (tommos.ai) is a CRM whose AI agents, the tommos, take a B2B inquiry to a signed contract. On the Sign plan, Tommo Closer makes sure that the reminders after the due date never depend on someone remembering a date. It prepares each invoice the day its amount falls due, and when the due date passes unpaid, it has the payment reminder email written, from the deal’s record, on the right day. The setup, once:
- 1
Connect Mercury
In Settings, Invoices, copy the address under “First, in Mercury, allow this address on the token”, allow it on your Mercury API token, then paste the token and press “Connect Mercury”. Tommos then reads each invoice’s status, so a paid invoice never gets a reminder.
- 2
Accept the payment schedule
When a deal is won, Tommo Closer reads the signed SOW and puts the payment schedule on a card: each amount, its date or event, its payment term. Accept it or change it. The due dates of every reminder come from here.
- 3
Send each invoice from its card
When an amount falls due, the invoice waits on a card with the PO number and the letter that carries it. Press “Make the invoice”, check the PDF, then “Send”. Letters 1 to 3 of this page go before the due date, so you send them yourself, in the thread of the invoice letter.
- 4
Set the reminders after the due date
Open Tommo Closer, the job “Get the deal paid”, its Letter. Under “When it reminds of an unpaid invoice”, set “First, days after the due date”, “Then every, days” and “At most” (3, 7 and 3 by default). In “How this job takes this act, in your words”, write the tone you want: short, the invoice number and PO in the subject, AP in To and your contact in Cc.
- 5
Press Send on the day
On the day a reminder is due, it waits on a card on your phone, already written. Send it, change a line or skip it; one press sends it, and nothing goes to the client on its own. After the last reminder, a person gets a task.
Questions about payment reminder emails#
- How do I write a friendly payment reminder email?
- Keep it to three or four lines: the invoice number, the PO, the amount, the due date and a payment link, then one question, such as "Is it approved for your payment run before that date?" Attach the PDF again and copy your contact.
- When should I send a payment reminder?
- Two or three business days after the invoice to confirm it arrived, seven days before the due date, and on the due date. After that, the letters are overdue reminders, three, ten and thirty days late.
- Is it rude to send a payment reminder before the invoice is due?
- No. A reminder before the due date gives the client time to fix a missing approval or PO. A payables team would rather fix it then than after the date, when the fix takes another payment cycle.
- What is a good subject line for a payment reminder?
- One with the invoice number and the date: "Invoice INV-2026-031 due November 19". The clerk can match it without opening the email.
- Should I resend the invoice with each reminder?
- Attach the PDF again to the first two letters. The first copy may sit in your contact's inbox, not in AP's. On the due date, the payment link alone is enough.
- How many payment reminders should I send?
- Three before the due date and up to three after it. After a final notice with no answer, stop writing and call: one more email rarely moves an invoice that six did not.
- Can I automate payment reminders?
- Yes, as long as every reminder still carries the invoice number, the PO and the payment link, and stops the moment the invoice is paid. On the Sign plan, Tommo Closer writes the reminders after the due date as cards: by default 3 days late, then every 7 days, 3 in all, and none once your invoice system shows the invoice paid.
- Should a payment reminder mention late fees?
- Only after the due date, and only when the contract or the invoice terms set a late fee. Before the due date, a fee line reads as a threat to a client who has done nothing wrong.
- Who should I send the payment reminder to?
- To the AP inbox or the person who processes supplier invoices, with your contact in Cc. If there is no AP team and your contact approves the payment, write to your contact directly.
Key takeaways#
- Send three letters before the money is late: the receipt check, the week-before note, the due-date line.
- Put the invoice number, PO, amount, due date and link in the body and the subject.
- Ask one question in each letter: is it in your system, is it approved.
- Write to AP and copy your contact.
- If the day passes, move to the overdue letters three days later.
Read next
- How to get clients to pay on timeThe eight steps from the signed SOW to the money, the vendor setup email and the invoice checklist.
- Overdue invoice email: what to send 3, 10 and 30 days lateWhy invoices go overdue, the letter for each week, and the fixes for a missing PO, a wrong entity or a disputed line.
- Net 60 payment termsThe cash math of net 60, the counter-wording, and the email that asks for net 30.