Every company should list its company registration number, place of registration, and registered office address on its website as a result of an update to the legislation of 1985. The information, which must be in legible characters, should also appear on order forms and in emails. Such information is already required on "business letters" but the duty is being extended to websites, order forms and electronic documents.

The change is being made by a Statutory Instrument that is expected to be passed on Thursday to implement a European law, the First Company Law Amendment Directive, into UK law. According to a Department of Trade and Industry spokesperson, the law will take effect on 1 January, one day later than the Directive requires.

The information is likely to appear in the footer of every email sent from a company, to avoid having to decide whether each email amounts to a "business letter" or not. Many companies do this already because the term "business letters" was thought likely to include emails even without this new clarification.

For websites, contrary to the fears of some, the specified information does not need to appear on every page. Again, many websites will already list the required information, perhaps on their "About us" or "Legal info" pages.