To register a charge created before 6 April 2013 subject to which property has been acquired, use form MG06 (England and Wales, Northern Ireland) or form MG06s (Scotland), which can be found on the National Archives website.
It costs £23 to register a charge, regardless of when the charge was originally created.
Message added: Due to essential maintenance Companies House online services will be unavailable between Saturday 16 April 2016 and Sunday 17 April 2016. Please accept our apologies for any inconvenience this may cause. You’ll still be able to file with HMRC.