A one-person business should build its invoice around the rules applying where it is registered and where the customer is located. Australia has tax-invoice rules with a threshold of A$1,000, the UK permits simplified invoices for supplies of £250 or less including VAT, and Singapore permits a simplified tax invoice when the total payable including GST does not exceed S$1,000. These figures and requirements come from the Australian Taxation Office, HM Revenue & Customs and the Inland Revenue Authority of Singapore, respectively, checked 2026-10-01.
No mandatory invoice format or required field list was found on the official Hong Kong or US federal pages reviewed for this article, checked 2026-10-01. This means that no statutory format can be confirmed from those sources—not that one does not exist.
Which invoice rules apply to your business?
Start with your tax status, the customer’s tax status, the transaction and its value.
| Jurisdiction | When the following requirements apply |
|---|---|
| Australia | The details below apply to tax invoices for taxable sales. Regular invoices for businesses not registered for GST follow different rules. |
| United Kingdom | The VAT-invoice requirements apply to VAT-registered businesses. The position of a non-VAT-registered sole trader is not stated on the official page reviewed. |
| Singapore | The tax-invoice requirements apply to GST-registered businesses invoicing customers covered by those requirements. |
Sources: Australian Taxation Office, HM Revenue & Customs and Inland Revenue Authority of Singapore; checked 2026-10-01.
What should an Australian tax invoice contain?
Which fields are required for a taxable sale under A$1,000?
For a taxable sale of less than A$1,000, the Australian Taxation Office says the invoice must provide enough information to determine these matters:
- The document is intended to be a tax invoice.
- The seller’s identity.
- The seller’s Australian business number.
- The invoice issue date.
- A brief description of the items, including quantity where applicable and the price.
- The GST amount, if any.
- The extent to which each sale on the invoice is taxable.
Source: Australian Taxation Office, Tax invoices; checked 2026-10-01.
Does an invoice over A$1,000 need anything else?
Yes. A tax invoice for A$1,000 or more must also show the buyer’s identity or ABN. No further mandatory fields beyond those stated on the Australian Taxation Office page are added here.
Source: Australian Taxation Office, Tax invoices; checked 2026-10-01.
How should GST be shown?
The GST amount can be shown separately. If it is exactly one-eleventh of the total price, the invoice may instead state “Total price includes GST”.
Where the invoice includes both taxable and non-taxable items, it must clearly identify the taxable items and show:
- Each taxable sale.
- The GST payable.
- The total amount payable.
If there is only one taxable sale, GST is rounded to the nearest cent, with 0.5 cents rounded upwards.
Source: Australian Taxation Office, Tax invoices; checked 2026-10-01.
When must an Australian tax invoice be provided?
If a customer asks for a tax invoice, it must be provided within 28 days, unless the sale is A$82.50 including GST or less. A GST-registered business must issue a tax invoice for a taxable sale over A$82.50 including GST.
Sources: Australian Taxation Office, Tax invoices, and business.gov.au, How to invoice; checked 2026-10-01.
What if the business is not registered for GST in Australia?
There is no law setting out the contents of a regular invoice on the Australian Government page reviewed. It must say “invoice” and must not say “tax invoice”.
If GST turnover is under A$75,000 and the business has not chosen to register, its invoices must show that GST was not included. A unique invoice number, contact details and payment terms are recommended good practice, not mandatory fields under that page.
Sources: Australian Government, How to invoice and Register for goods and services tax (GST); checked 2026-10-01.
Does an Australian tax invoice have to be on paper?
No. It may be issued as an emailed PDF or in another digital format, provided that it contains all the information required for a valid tax invoice.
Source: Australian Taxation Office, Tax invoices; checked 2026-10-01.
What must a UK VAT invoice contain?
What are the full VAT-invoice fields?
A VAT-registered business issuing a full VAT invoice must show:
- A sequential number based on one or more series that uniquely identifies the document.
- The time of supply.
- The issue date where it differs from the time of supply.
- The supplier’s name, address and VAT registration number.
- The customer’s name and address.
- A description sufficient to identify the goods or services.
- For each description, the quantity of goods or extent of services.
- The VAT rate and amount payable excluding VAT.
- The gross total payable excluding VAT.
- Any cash-discount rate.
- The total VAT chargeable in sterling.
- The unit price.
Source: HM Revenue & Customs, Record keeping (VAT Notice 700/21); checked 2026-10-01.
When must a UK VAT invoice be issued?
A VAT-registered business must issue a VAT invoice when it supplies standard-rate or reduced-rate goods or services to another VAT-registered person. Normally, the invoice must be issued within 30 days of the supply.
Source: HM Revenue & Customs, Record keeping (VAT Notice 700/21); checked 2026-10-01.
Can a smaller invoice be used in the UK?
If the business is not a retailer and the total supply value is £250 or less including VAT, it may issue a simplified invoice containing:
- Supplier name, address and VAT registration number.
- Tax point.
- Description identifying the goods or services.
- For each applicable VAT rate, the total payable including VAT in sterling.
- The VAT rate charged.
For a supply over £250, a full or modified VAT invoice is required. A VAT invoice is not always required for exempt or zero-rated sales within the UK.
Source: HM Revenue & Customs, Record keeping (VAT Notice 700/21); checked 2026-10-01.
Are margin-scheme and reverse-charge invoices different?
Yes. Special rules apply to invoices issued under a margin scheme or subject to a reverse charge. A full VAT invoice may also need a relevant reference or indication identifying either treatment.
Sources: HM Revenue & Customs, Record keeping (VAT Notice 700/21) and VATREC5010; checked 2026-10-01.
A VAT-registered business must also keep a copy of every VAT invoice it issues.
Source: HM Revenue & Customs, Record keeping (VAT Notice 700/21); checked 2026-10-01.
What must a Singapore tax invoice contain?
Which fields must appear?
A Singapore tax invoice must contain:
- The words “Tax Invoice”.
- The supplier’s name and address.
- The supplier’s GST registration number.
- The invoice date.
- An invoice-identifying number.
- The customer’s name and address.
- A description of the goods and services.
- The GST rate.
- The total payable excluding GST.
- The total GST.
- The total payable including GST.
Source: Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
How should mixed or special supplies appear?
If applicable, the invoice must give details of exempt, zero-rated or other supplies. The gross amount payable for each type of supply must be stated separately.
Source: Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
When must a Singapore tax invoice be issued?
A tax invoice must be issued when the customer is GST-registered. In general, it must be issued within 30 days from the time of supply.
A tax invoice is not required for zero-rated supplies, exempt supplies, deemed supplies or for non-GST-registered customers.
Source: Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
Can a simplified Singapore tax invoice be used?
If the total payable including GST does not exceed S$1,000, a simplified tax invoice may contain:
- Supplier name, address and GST registration number.
- Invoice issue date.
- An identifying number.
- Description of the goods or services.
- Total payable including GST.
- A statement such as “price payable includes GST”.
Source: Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
If the invoice uses a foreign currency, the total excluding GST, total including GST and total GST must also be converted into Singapore dollars using approved exchange rates.
Source: Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
Singapore tax invoices must be kept for at least 5 years. GST-registered businesses must transmit invoice data to IRAS using InvoiceNow-Ready Solutions, with mandatory participation implemented in phases.
Source: Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
What should a reusable sole trader invoice template contain?
Use the applicable jurisdiction’s mandatory fields first, then add operational details only where they help the customer or the business.
Australia
- Correct document wording: “Tax Invoice” or “invoice”, depending on the circumstances.
- Seller’s identity and ABN where required.
- Invoice date.
- Item description, quantity where applicable and price.
- Tax treatment of each sale.
- GST amount or the permitted GST-inclusive statement.
- Buyer’s identity or ABN for a taxable sale of A$1,000 or more.
- Total amount payable where taxable and non-taxable items appear together.
- Recommended additions: unique invoice number, contact details and payment terms.
Sources: Australian Taxation Office and Australian Government, How to invoice; checked 2026-10-01.
United Kingdom
- Sequential invoice number.
- Time of supply.
- Issue date where different.
- Supplier name, address and VAT registration number.
- Customer name and address.
- Description, quantity or service extent, VAT rate, unit price and VAT-exclusive amount.
- Gross VAT-exclusive total.
- Cash-discount rate, if offered.
- Total VAT in sterling.
- Margin-scheme or reverse-charge reference where applicable.
Source: HM Revenue & Customs, Record keeping (VAT Notice 700/21); checked 2026-10-01.
Singapore
- The words “Tax Invoice”.
- Supplier name, address and GST registration number.
- Invoice date and identifying number.
- Customer name and address.
- Goods or services description.
- GST rate.
- Total excluding GST, total GST and total including GST.
- Separate gross amounts for exempt, zero-rated or other supplies where applicable.
- Singapore-dollar equivalents for the three totals when invoicing in a foreign currency.
Source: Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
Frequently asked questions
Does a sole trader need an invoice number?
It depends on the jurisdiction and invoice type. Australia recommends a unique invoice number for regular invoices, while the UK requires a sequential identifying number on a full VAT invoice and Singapore requires an invoice-identifying number on a tax invoice.
Sources: Australian Government, How to invoice; HM Revenue & Customs, Record keeping (VAT Notice 700/21); Inland Revenue Authority of Singapore, Invoicing Customers; checked 2026-10-01.
Can a one-person business send an electronic invoice?
Australia expressly permits an emailed PDF or another digital format if it contains all required tax-invoice information. Whether an electronic invoice is accepted in the UK or Singapore is not stated on the official pages reviewed, checked 2026-10-01.
What is the smallest invoice allowed in Australia?
The Australian Taxation Office says a requested tax invoice must generally be provided within 28 days, except where the sale is A$82.50 including GST or less. It does not describe that amount as permission to omit required tax-invoice fields.
Source: Australian Taxation Office, Tax invoices; checked 2026-10-01.
Must a customer’s name appear on every invoice?
For a full Singapore tax invoice, the customer’s name must appear. In the UK, a full VAT invoice requires the customer’s name and address. Australia’s ATO page states that the buyer’s identity or ABN is additionally required for tax invoices of A$1,000 or more.
Sources: Inland Revenue Authority of Singapore, Invoicing Customers; HM Revenue & Customs, Record keeping (VAT Notice 700/21); Australian Taxation Office, Tax invoices; checked 2026-10-01.
Is there an official invoice template for Hong Kong or the United States?
A mandatory invoice format or required field list was not found on the Hong Kong or US federal official pages reviewed, checked 2026-10-01. No official mandatory format is claimed here.