よさげなサイト発見。

Invoice – How to start small business – Small business start up information

まだちゃんと読んでないが、とりあえず要点だけ。

Contents of an invoice
In commercial practice, an invoice should include the following items:

* Date of issue
* Date of supply
* Names and addresses of the suppliers and recipients
* Description of the goods or services supplied including quality, quantity and unit prices
* Terms of sale, due date for payment and whether any discount is available and
* Amount payable

請求書にはこんなんを含めればいいそうです。

ページの下の方に、pdfのサンプルもついてた。
なーいす。