# What is a sales invoice? Required fields and a worked example

> A sales invoice is the bill a seller sends a buyer. See the fields the UK and Germany require, a filled-in example and how tax fits.

Canonical: https://www.invoqk.com/blog/what-is-a-sales-invoice-required-fields-and-a-worked-example
Last updated: 2026-10-31

## Key takeaways

- A sales invoice is a document a seller sends a buyer listing what was sold, the price and the due date.
- GOV.UK requires a unique number, both parties' details, a description, supply date, invoice date, amounts and the total owed.
- German invoices under section 14(4) UStG also need the supplier's tax number or VAT ID and a tax rate and amount split.

**A sales invoice** is a document a seller sends a buyer that lists what was sold, what it costs and when payment is due. If you are holding a blank page and need to send one today, the fields below and the worked example cover what most freelancers and small businesses need.

This guide covers the United States, the United Kingdom and Germany. It states the rules as the authorities publish them and does not give advice on your own tax position.


## What is a sales invoice?

**A sales invoice** is the seller's request for payment for goods or services already supplied. Many buyers also call it a customer invoice, client invoice, billing invoice, bill or service invoice. They all mean the same thing: a record of the sale that the buyer pays against and both sides keep for their books.

**A receipt** is a record that payment arrived, so a sales invoice is not a receipt. [GOV.UK](https://www.gov.uk/invoicing-and-taking-payment-from-customers) states that an invoice is not the same as a receipt, which is an acknowledgement of payment. The invoice asks for money. The receipt confirms it arrived.

## What must a sales invoice include?

A sales invoice must carry identifying details for both parties, a description of the sale, the amounts and the dates. GOV.UK lists the following for every UK invoice in its [guidance on what invoices must include](https://www.gov.uk/invoicing-and-taking-payment-from-customers/invoices-what-they-must-include).

1. A unique identification number.
2. Your company name, address and contact information.
3. The name and address of the customer you are invoicing.
4. A clear description of what you are charging for.
5. The date the goods or service were provided (the supply date).
6. The date of the invoice.
7. The amount or amounts being charged.
8. The VAT amount, if applicable.
9. The total amount owed.

Sole traders in the UK must also add their own name and any business name they use. Limited companies must use the full company name as it appears on the certificate of incorporation, according to GOV.UK.

## What does Germany require on a sales invoice?

[Section 14 of the German VAT Act (UStG)](https://www.gesetze-im-internet.de/ustg_1980/__14.html) sets the mandatory details for an invoice. The list is close to the UK one, with a few extras.

| Required detail under §14(4) UStG | Plain meaning. |
|---|---|
| Full name and address of supplier and recipient | Both parties, in full. |
| Tax number or VAT ID of the supplier | Steuernummer or USt-IdNr. |
| Invoice date | The day you issue it. |
| Sequential invoice number | One unique, running number. |
| Quantity and type of goods, or scope of services | What was sold. |
| Date of delivery or service | When the supply happened. |
| Consideration split by tax rate and any exemption | Net amounts per rate. |
| Tax rate and tax amount, or an exemption notice | The VAT line, or the reason for none. |

[Section 12 UStG](https://www.gesetze-im-internet.de/ustg_1980/__12.html) sets the general German VAT rate at 19 percent and the reduced rate at 7 percent. A German invoice that charges VAT has to show which of those rates applies to each line.

## What does the US require on a sales invoice?

The United States has no single federal list of invoice fields. The [IRS recordkeeping page](https://www.irs.gov/businesses/small-businesses-self-employed/recordkeeping) says you may choose any recordkeeping system suited to your business that clearly shows your income and expenses. It also says you must keep records as long as needed to prove the income or deductions on a tax return.

In practice a US sales invoice carries the same core fields as the UK list. Add a sales tax line only where your state taxes the item you sold. Check the rule with your state tax agency, because it varies by state and by product.

## Worked example: a sales invoice for a service

For example, a worked invoice shows how the fields fit together. This US example bills a web design client in US dollars.

| Field | Entry. |
|---|---|
| Invoice number | INV-2026-014. |
| Invoice date | October 7, 2026. |
| Service date | September 22 to October 3, 2026. |
| Seller | Harbor Web Studio, 41 Pier Lane, Portland, OR. |
| Buyer | Alder Coffee Roasters, 9 Mill Street, Salem, OR. |
| Line 1 | Website redesign, 10 hours at $90.00 = $900.00. |
| Line 2 | Hosting setup, flat fee = $150.00. |
| Subtotal | $1,050.00. |
| Tax | $0.00 (no tax line for this service). |
| Total due | $1,050.00. |
| Payment terms | Net 30, due November 6, 2026. |

The same sale billed in Germany to a business customer would add the supplier's VAT ID and split the net amount by rate. At the 19 percent general rate, a net amount of €1,050.00 carries €199.50 of VAT and totals €1,249.50. In the UK at the [20 percent standard rate](https://www.gov.uk/vat-rates), a net £1,050.00 carries £210.00 of VAT and totals £1,260.00.

Invoqk can fill in a layout like this from a short job description, so you only check the numbers before sending.

## How do you write a sales invoice step by step?

A sales invoice takes six steps once you know the fields.

1. Give the invoice a unique number from a running sequence.
2. Enter both parties' full names and addresses.
3. Add the invoice date and the date the work or delivery happened.
4. List each line with a clear description, quantity and price.
5. Add tax only where the rules of your country require it.
6. State the total, the due date and how to pay.

Not sure how detailed a description should be? Keep it plain. "Website redesign, 10 hours" beats "services rendered", because the buyer's accounts team has to match it to a purchase.

## Sales invoice mistakes that delay payment

Why do small invoices get paid late? Most delays trace back to a few avoidable gaps.

- **No due date.** A buyer with no date has no deadline. State the date, not only "Net 30".
- **Wrong or missing buyer name.** Accounts teams cannot book an invoice addressed to the wrong entity.
- **Repeated numbers.** A reused invoice number looks like a duplicate and gets held.
- **No payment instructions.** Add bank details or a payment link on the invoice itself.

For deposits and part payments, see how the [Quote template: what to include, with a free example](/blog/quote-template-what-to-include-with-a-free-example) turns an accepted offer into a first invoice. If you also need to confirm payment afterwards, the [Online receipt generator: how to make a valid receipt](/blog/online-receipt-generator-how-to-make-a-valid-receipt) shows what a receipt adds.

## FAQ

### What is the difference between a sales invoice and a bill?

A sales invoice is what the seller sends. A bill is the same document seen from the buyer's side, once it lands in their accounts payable. The paper is identical, and only the role of the person holding it differs.

### Is a sales invoice the same as a client invoice?

Yes. A client invoice, customer invoice and billing invoice are all names for a sales invoice. The label changes by industry, while the required fields stay the same under the rules of the country issuing it.

### Does a sales invoice need VAT or sales tax?

Only where your country's rules and your registration require it. UK VAT-registered sellers show the VAT amount, German invoices show the tax rate and amount or an exemption notice, and US sales tax depends on your state.

### Can I edit an invoice after sending it?

Do not change a sent invoice. Issue a credit note for the original and send a corrected invoice with a new number. That keeps the numbering unbroken and the records clean for both sides.

## Related

- [Free invoice template guides: compliance & getting paid](https://www.invoqk.com/blog)
- [Invoqk home](https://www.invoqk.com)