We have recently changed the format of our standard and self-billing invoices from HTML to PDF.
PDF is undoubtedly one of the most commonly used electronic document formats. Documents can be viewed on a wide range of platforms, including Windows, MacOS, Unix and several others. It provides users with an open ISO-standard format for document exchange, and has become more popular as the internet has grown. A number of major institutions now use PDF documents for their operations, alongside, or even replacing, paper documentation.
Changing to PDF ensures that invoices maintain a consistent layout, independent of browser, and are not editable without the use of specialist software, while making it easier to share or forward these documents. The popularity of the format also means your invoices will most likely now be in the same format as a lot of current electronic documentation.
HTML versions of invoices can still be viewed online.