Invoicing customers

Tax invoices, customer accounting tax invoices, receipts and credit notes are common documents issued when billing your customers. These documents serve as important records of business transactions between you and your customers.

Tax invoice/customer accounting tax invoice

A tax invoice/ customer accounting tax invoice is the main document for supporting an input tax claim.

You must keep these tax invoices issued to your customers, and those given to you by your suppliers, for at least 5 years. You do not need to submit them with your GST returns.

When to issue a tax invoice

A tax invoice must be issued when your customer is GST registered. Your customer needs to keep this tax invoice as a supporting document to claim input tax on its standard-rated purchases. In general, a tax invoice must be issued within 30 days from the time of supply .

A tax invoice does not need to be issued for zero-rated supplies , exempt supplies and deemed supplies or to a non-GST registered customer.

A tax invoice must contain the following information:

The tax invoice must also provide details on exempt, zero-rated, or other supplies, if applicable. The gross amount payable for each type of supply must be separately stated.

When you invoice your customer in a foreign currency, you must convert the following items on the tax invoice into Singapore dollars:

  • Total amount payable excluding GST
  • Total amount payable including GST
  • Total GST payable

Your GST-registered customer (subject to the fulfilment of the input tax claiming conditions) can only claim input tax based on the amounts stated in the tax invoice issued by you, the supplier. Please note that you must use approved exchange rates for GST purpose (PDF, 185KB) for the conversion.

Calculate GST on tax invoices

There are 2 ways to compute the total GST amount on your tax invoice when your customer purchases several items of standard-rated supplies:

  1. Apply 7% to the value of each item (excluding GST), and then sum the GST computed for each item

  2. Apply 7% to the sum of the value of each item (excluding GST) 

The total GST computed may differ due to rounding because of the method you have chosen. Both methods are acceptable and you must apply the chosen method consistently.

You are a stationery retailer. Your customer purchased 3 pens. The tax invoice issued to your customer may contain the following:

ItemQuantityAmount Payable (excluding GST)GST Amount for Each Item

Green pen



$0.09 ($1.33 X 7%)

Red pen



$0.09 ($1.33 X 7%)

Blue pen



$0.09 ($1.33 X 7%)




= $0.27 ($0.09 + $0.09 + $0.09)

Total Payable



= $4.26 ($3.99 + $0.27)

You are a stationery retailer. Your customer purchased 3 pens. The tax invoice issued to your customer may contain the following:

ItemQuantityAmount Payable (including GST)

Green pen



Red pen



Blue pen





$3.99 ($1.33 + $1.33 + $1.33)

GST @ 7%


= $0.28 ($3.99 X 7%)

Total Payable


= $4.27 ($3.99 + $0.28)

Rounding off total GST

You can round the total GST to be paid on all goods and services to the nearest cent (i.e. two decimal places).

You may also choose to round your total bill (i.e. total amount payable including GST) to the nearest 5 cents to facilitate cash payment by your customers.

Whether a bill should be rounded up or rounded down to the nearest 5 cents is your business decision. However, the decision for the amount to be rounded up or down must be applied consistently. 

When to issue a customer accounting tax invoice

You must issue a customer accounting tax invoice, instead of a regular tax invoice, when you make a relevant supply that is subject to customer accounting to your GST-registered customer.

Your GST-registered customer needs to keep this customer accounting tax invoice as a supporting document to account for the output tax on this supply on your behalf, as well as to claim the input tax on this purchase.

For information on what you must include on a customer accounting tax invoice, you may refer to our e-Tax Guide on  GST: Customer Accounting for Prescribed Goods (PDF, 434KB).


Simplified tax invoice for amounts under $1,000

You may issue a simplified tax invoice instead of a regular tax invoice if the total amount payable for your supply (including GST) does not exceed $1,000.

A simplified tax invoice only requires the following information:

  1. Supplier's name, address and GST registration number
  2. Date of issue of invoice
  3. An identifying number (e. g. invoice number)
  4. Description of the goods or services supplied
  5. Total amount payable including GST
  6. A statement similar to "price payable includes GST"

A sales voucher or debit note can double up as a simplified tax invoice if it contains all the required information above.

Invoice for an exempt supply of investment precious metal (IPM)

An invoice must be issued for an exempt supply of investment precious metal (IPM) . The GST: Guide on Exemption of Investment Precious Metals (IPM) (PDF, 389KB) lists the information you must include on an invoice issued for an exempt supply of IPM.


You may issue a receipt instead of a tax invoice to your non-GST registered customer. Receipts can be used as proof of your sales made to customers. You must retain a duplicate of the receipt issued.

A receipt must be serially printed and have all the following details:
1. Date of issue of the receipt
2. Your business name and GST registration number
3. The total amount payable (including the total amount of GST chargeable)
4. The words "Price payable includes GST"

    You do not need IRAS’ approval if you choose not to issue receipts. However, you must keep proper records on all business transactions for tax purposes You can use either a cash register or accounting software to help you maintain your business records.

    Please note that:
    • If requested by customers, you must still issue receipts.
    • You must still issue tax invoices to GST registered customers, as explained in the section on when to issue a tax invoice.

    You should ask for a receipt when you make a purchase for business purposes whether you pay by cash or cheque. The receipt serves as proof of payment made to and received by your supplier.

    Credit note

    When to issue a credit note

    A credit note is issued to correct a mistake or to give a credit to your customer under the following situations:

    1. To correct a mistake (e.g. goods invoiced as standard-rated, which should have been exempt or zero-rated);
    2. Goods or services were not supplied;
    3. Charges are partly or fully waived before/after delivery of the goods;
    4. Goods or services are accepted, but terms of the contract are not fully met (e.g. sub-standard goods are accepted by the customer at a reduced price);
    5. Goods are returned or services are not accepted; or
    6. Discount given for a past transaction.

    A credit note must include the following details:

    1. An identifying number e.g. a serial number
    2. Date of issue
    3. Your name, address and GST registration number
    4. Your customer's name and address
    5. Reason for the credit, e.g. "returned goods"
    6. Detailed description to identify the goods and services that credit is allowed for
    7. Quantity and amount credited for each description
    8. Total amount credited, excluding tax
    9. Rate and amount of tax credited
    10. Total amount credited, including tax

    The number and date of the original tax invoice should also be shown on the credit note. If you are unable to do so (e.g. because returned goods cannot be identified with a particular tax invoice), you must maintain other documentary evidence that you have accounted for GST on the original supply.

    Declaring credit note in GST returns

    Adjustments should be made to the value of standard-rated supplies (Box 1) and output tax due (Box 6) in the GST return for the accounting period in which the credit note is issued.

    You should also check that GST was correctly accounted for on the original transactions in your earlier returns before making the adjustments. If GST was not accounted for correctly, you need to correct the errors made for the earlier returns.

    For credit notes issued relating to customer accounting supplies, you may refer to GST: Customer Accounting for Prescribed Goods to learn how the adjustments should be made.

    If you issue a credit note on 30 Jun 2021 for a sale made on 1 Jan 2021 (assuming that GST had been correctly accounted), you should reduce your value of standard-rated supplies (Box 1) and output tax due (Box 6) accordingly in the GST return for the accounting period covering Jun 2021.

    Choosing not to adjust the GST amount when issuing a credit note

    In your credit note, you can choose not to adjust the GST amount charged on the original tax invoice if all the following conditions are satisfied:

    • Both supplier and customer agree in writing not to adjust the original GST amount. This written agreement does not need to be a formal contract. It could be the correspondence between supplier and customer via letters or emails. Both parties must retain the written agreement as part of their GST records. The written agreement does not need to be submitted to IRAS, unless requested.
    • Customer is a fully taxable person (i.e. does not make any exempt supplies).
    • The credit note, which is issued without any adjustment to the original GST amount, should contain the statement "This is not a credit note for GST purposes". If such credit notes are issued by the supplier, both the supplier and customer do not need to adjust the value of their taxable supplies/ purchases or the related output/ input tax.

      Debit note

      You should only issue a debit note to request for payment for transactions where no GST is charged (e.g. internal billings within the same company), or to suppliers from whom credit is due.

      For all other standard-rated supplies to GST-registered customers, you must issue a tax invoice or simplified tax invoice (where the total amount payable including GST does not exceed $1,000). This enables your customer to support his input tax claims.

      Issuing debit note to record credit received from suppliers

      A record of all credits received from your suppliers must be kept. If you normally issue debit notes to suppliers from whom credit is due, the debit notes must show the same details required for credit notes.

      If credit notes are subsequently received from the suppliers, they should be compared with the debit notes issued to ensure that the figures match.


      Updated!Self-billing is a billing arrangement between a GST-registered supplier and a GST-registered customer, where the customer, instead of the supplier, prepares the supplier's tax invoice/ customer accounting tax invoice and sends a copy to the supplier. Please refer to the samples of the self-billing tax invoice (PDF, 93KB)

      In some industries (e.g. publication industry), the business arrangement is such that customers, instead of the supplier, will determine and verify the final value of the goods delivered or the services rendered to them. Hence, it is more convenient for the customer, rather than the supplier, to issue the tax invoice/customer accounting tax invoice.

      Customers that prescribe purchase documentation for their suppliers may also prefer self-billing to facilitate their internal controls and accounting system.

      Before you apply for self-billing, you should consider the following points:

      • You will have added responsibilities to ensure that the conditions of self-billings are satisfied
      • You will have to ensure that the GST amount is correctly calculated for the goods and services supplied to you
      • You will have to ensure that any errors made on buyer-created tax invoices/ customer accounting tax invoices are corrected and the supplier is duly informed

      To adopt self-billing, the customer must complete and submit the Self-Review of eligibility and declaration on use of self-billing form,after verifying that all conditions in the form are satisfied.

      The customer can adopt self-billing from the date of submission of the form, based on its declaration that all conditions in the Form has been satisfied. No further approval is required from IRAS.

      If you have previously received IRAS' approval for self-billing, you may continue to self-bill as long as you still satisfy the conditions in the Form. You do not need to submit the Form again.

      You do not need to submit your updated list of suppliers covered by the self-billing arrangement but should retain the updated list as your business records.