Why adding a QR code speeds up payment
How fast a client pays isn't only about intent — it's about how many steps stand between them and the transfer. An invoice with just an account number forces the payer to type the number, verify the name, enter the amount, and hope they didn't fat-finger a digit. An invoice with a PromptPay QR that already carries the amount takes a scan and a confirm.
For freelancers billing small business owners or individuals, that difference often means paid today instead of paid next week. Here's the practical setup, plus the mistakes that show up most.
Step 1: Point PromptPay at the right account
Register PromptPay against the account you use for work only — not the one you also buy groceries with. This isn't about tidiness. At year end, nearly every credit on that statement will be genuine income, which makes reconciling and explaining the money far easier.
The mistake people make most: the account name must match the payee name on the invoice. Plenty of corporate accounting teams are forbidden from transferring to an account whose name doesn't match the contracting party. If your invoice is in your name but the QR points to your partner's account, the paperwork bounces.
Step 2: Pick the right kind of QR
Two options:
- Amount-free QR — generate once, reuse everywhere, but the client types the amount themselves. This is where short and over-payments come from.
- Amount-embedded QR — generated per invoice; the client scans and the figure is already there. Nearly eliminates entry errors.
Use amount-embedded for invoices, every time. Keep the amount-free one for small deposits or tips.
Step 3: Embed the amount they actually need to transfer
This is the step people get wrong, because the invoice total and the transfer amount usually aren't the same number.
Not VAT-registered, corporate client
- Fee: THB 50,000
- Withholding tax 3% = THB 1,500
- Actual transfer = THB 48,500
VAT-registered, corporate client
- Fee: THB 50,000
- VAT 7% = THB 3,500 → THB 53,500
- Withholding 3% on the pre-VAT base = THB 1,500
- Actual transfer = THB 52,000
The key point: withholding is calculated on the pre-VAT amount, not the gross. If you embed the full total, a client doing it correctly will transfer a figure that doesn't match your QR — and the document comes back for correction.
Safest format: a small summary block at the bottom of the invoice showing subtotal, VAT, withholding, and amount due — then embed that final figure in the QR. For individual clients, who don't withhold, embed the full amount.
Step 4: Place the QR properly and label it
Bottom right of the invoice, next to the amount due — not on a separate final page. Add three short lines beside it:
- Account name and bank, for clients who still prefer to type it manually.
- "Please include document number INV-2026-014 in the transfer note."
- "Please send the transfer slip, and kindly issue the withholding tax certificate (50 ทวิ)."
That third line is the one that saves you in March. Asking for the WHT certificate while the client is in the act of paying is incomparably easier than chasing it six months later.
Step 5: Make reconciliation a weekly habit
Book ten minutes a week and do three things:
- Open the statement for your work account and review credits since last time.
- Match each credit to an invoice. If the amount is off, check first whether it's the 3% withholding or an interbank transfer fee before assuming a short payment.
- Mark matched invoices as paid and issue the receipt immediately.
Late receipts are quiet compounding debt. Issued on the day money arrives, it costs two minutes; issued retroactively in December, it costs a day.
Step 6: Pre-plan the follow-up rhythm
A QR reduces friction; it doesn't fix clients who forget. Fix the cadence in advance:
- 3 days before due: short reminder with the invoice attached again.
- On the due date: re-confirm the amount and resend the QR.
- 7 days overdue: contact accounting directly, not the person who hired you — they're usually not the one releasing payment.
- 15 days overdue: reference the payment terms in the quotation they approved.
Common mistakes
- Treating the transfer slip as a tax document. It isn't. A slip is proof of payment; the tax document is your receipt, plus a tax invoice if you're VAT-registered.
- Reusing one QR across every job, so you can't tell which project a payment belongs to — painful when one client runs several projects at once.
- Forgetting daily transfer limits. Large invoices can exceed the client's app limit; offer a counter transfer or a milestone split before it becomes a delay.
- Embedding a low-resolution QR image that won't scan off a phone screen. Test-scan the actual PDF before sending, every time.
Checklist
- PromptPay points to the work account, and the name matches the invoice
- Amount-embedded QR, carrying the post-withholding figure
- Summary block: subtotal / VAT / 3% withheld / amount due
- Note requesting the document number in the transfer reference, and the WHT certificate
- Weekly reconciliation, receipt issued the day money lands
- Follow-up cadence at −3 days, due date, +7, +15
In MANA, the quotation, invoice, and receipt sit on one chain belonging to the same job, with payment details carried on the document — so when you reconcile, you're never guessing which project a deposit came from.