A Singapore invoice must show the supplier, the customer, a unique number, the date, a description, the amount in Singapore dollars and, for GST-registered suppliers, the words Tax Invoice with the GST registration number. PayNow lets customers pay by QR code or UEN, so print the payment details on the invoice itself.
For a business not registered for GST, a normal commercial invoice is enough. Show your legal name or business name, UEN and address, the customer's name and address, a unique invoice number, the date, a description of the goods or services, the amount payable and the payment terms.
A GST-registered supplier issues a tax invoice. It must carry the title Tax Invoice, the supplier's GST registration number, the customer's details, the date of supply and issue, the description, the quantity or extent of the supply, the price before GST, the GST amount and the total. A simplified tax invoice is allowed for lower-value supplies within limits set by IRAS.
A tax invoice must be issued within 30 days of the supply. The customer needs it to claim input tax, so a late or incomplete invoice is a problem for them as well as for you.
If the invoice is in a foreign currency, show the GST amount in Singapore dollars. Choose the exchange rate method with your accountant and apply it consistently.
Number invoices in a continuous sequence, with no gaps, so a reviewer can see that none are missing. If you need several series, such as one per entity or per branch, give each a clear prefix and keep a record of the rule.
State the payment terms on the invoice, such as 30 days from the invoice date, and make sure the contract says the same. A customer who disputes late fees will refer to the document they signed, not to the invoice footer.
Put the purchase order number on the invoice if the customer gave you one. Large companies often route invoices by PO number, and an invoice without it can sit in an approval queue for weeks.
Late-payment interest only works if it is agreed in advance. Add a clause to the contract or quotation, and mention the rate in the invoice footer so the customer cannot say it came as a surprise.
PayNow Corporate lets customers pay by entering the UEN, and many banks can generate a QR code that carries the amount and a reference. Printing the code on the invoice cuts the typing errors that cause misapplied payments.
SGQR is the unified QR standard in Singapore, so a single code can be read by several banking apps. A dynamic QR can carry the invoice number as the reference, which removes the matching guesswork.
Bank transfer by account number remains common for larger payments and for foreign customers. List both options with the account name, bank and number, and ask customers to quote the invoice number.
A PayNow payment is instant but does not tell you which invoice it covers unless the sender types the reference. Check the reference field each morning.
Never overwrite an issued invoice. If the amount or description was wrong, issue a credit note that references the original invoice and then a new invoice. A GST-registered supplier must show the GST effect on the credit note, because the adjustment flows into the return for the period of the credit note.
A receipt is not required by GST law when a tax invoice has been issued, but customers often ask for one. A short confirmation that states the invoice number, the amount paid and the date received avoids repeat requests.
Keep an archive of every document issued, in a form you can search by number. When a customer says they never received invoice 214, a quick lookup of the sent copy settles the point in a minute.
When a customer overpays, decide at once whether to refund or to hold a credit against the next invoice, and tell them in writing. An unexplained credit sitting on the account is the item most likely to cause a dispute months later.
Send the invoice the day the work is delivered, not at month end. Each week of delay is a week added to the time it takes to be paid. Confirm receipt for large invoices and ask the customer for the date they expect to approve it.
Follow up in steps: a courteous reminder shortly before the due date, a firmer note the day after, then a call. A short message from a named person gets a response faster than an automated notice.
Record each reminder and the reply. If the debt later reaches a lawyer, the sequence of contact is evidence that you acted reasonably.
Ask large customers for the name and email of the person who approves payment. Sending invoices to a shared accounts inbox without that contact is the most common reason an invoice is unpaid for no reason.
4invoices.net creates PDF invoices with your UEN, GST number and payment details and keeps them in an archive. 4notify.net sends SMS and e-mail that you write from your account, for example to confirm that a PayNow payment has arrived.
4invoices has no PayNow integration, does not match payments by UEN and does not issue payment links in Singapore. Messages from 4notify are sent when you send them, not triggered by a payment event.
A sample workflow for a small firm: create the invoice from the job record, attach the PayNow QR code, send the PDF to the customer contact, then log the date sent. When the payment lands, tick it against the invoice and file the confirmation with it.
Review the archive monthly for invoices with no matching payment. The list is also the starting point for the chase calls.
PayNow credits arrive as generic bank notifications without an invoice reference number, requiring the accounts team to manually identify which open invoice each payment relates to — a task that falls to the end of the week when it is most error-prone.
Ask customers to quote the invoice number in the PayNow reference and match credits against your open invoices by hand. 4invoices has no PayNow integration or UEN-based matching.
Customers expect an instant digital receipt the moment their PayNow payment is confirmed, but generating and sending one manually for each transaction is impractical as invoice volumes grow.
Send a receipt or thank-you by SMS or e-mail from 4notify, written by you. Messages are not triggered automatically when a payment arrives.
The words Tax Invoice, the supplier's name, address and GST registration number, the customer's details, a unique serial number, the date, a description of the supply, the amount before GST, the GST amount and the total. A simplified tax invoice is permitted for lower-value supplies within IRAS limits. Issue it within 30 days of the supply.
Yes. A PayNow or SGQR code printed on an invoice is a normal way to collect payment, and it reduces typing errors. Generate it through your bank, check that it opens correctly in several banking apps and ask customers to keep the invoice number in the reference field so you can match the payment.
Yes, but if you are GST-registered the GST amount must also be shown in Singapore dollars. Use an exchange rate that IRAS accepts and apply the same method consistently. Record which rate and source you used, because your GST return is in Singapore dollars and a reviewer may ask how you converted.
Issue a credit note that refers to the original invoice number, then issue a new correct invoice. Do not edit or delete the original, because the sequence must remain complete for GST and audit purposes. A GST-registered supplier must show the GST amount on the credit note, which affects the return for that period.
GST law does not require a receipt when you have already issued a valid tax invoice, but customers often ask for proof of payment. A short confirmation stating the invoice number, amount and date received is enough. Keep a copy in the same archive so the invoice and its payment confirmation can be found together.
Issue PDF invoices and archive them. PayNow reconciliation is done from your bank statement.
