As a general rule the law requires that you deliver documents to Companies House in English.
However there are exceptions, companies can deliver some documents in languages other than English if the document is accompanied by a certified translation into English.
These include resolutions and agreements affecting a company's constitution delivered under Chapter 3 of Part 3 of the Companies Act 2006, a charge instrument or copy charge instrument, valuation report required to be delivered to the registrar under section 94(2)(d) of the Act, articles of association; Memorandum of association; and court orders.
Additionally you can file the accounts of larger EEA (European Economic Area) groups, the group accounts and parent undertaking's annual report; and accounts of larger non-EEA groups, the group accounts and, where appropriate, the consolidated annual report; in a language other than English of accompanied by a certified translation into English
In addition to their documents in English companies may also file voluntary certified translations of any document subject to the First Company Law Directive disclosure requirements. These include constitutional documents such as the memorandum and articles of association, directors appointments, changes in particulars or terminations, accounts, reports and annual returns, notification of any change in a company's registered office, winding up documents and documents relating to overseas companies
Public companies are also allowed to file voluntary certified translations of share capital documents and documents relating to mergers and divisions.
The regulations regarding these voluntary translations are that they must relate to a document delivered to Companies House on or after 1 January 2007, can only be filed in an official language of the European Union and must be accompanied by Form VT01, which will link the translation to the original document.
Welsh companies (those complying with section 88 of the Act) are entitled to draw up and deliver certain documents in Welsh without the need of an accompanying certified translation in English.