This is the retrospective approval for work already carried out without consent - and can only be administered by a Local Authority.
The Local Authority will assess, and verify by means of site visits, plans and information submitted, identify non-compliant items, open up and inspect works, monitor the making good of defective work and, if satisfied, issue a Certificate.
An application for a Regularisation Certificate does not prevent the Authority taking legal action for failure to comply with the Building Regulations when the work was first carried out.
These will vary depending on the size and value of the project, and between different Local authorities across the country, and each Approved Inspector is free to set their own levels of charges.
Some types of work may be exempt fees, e.g. adaptations or alterations for Disabled Persons.
If an Approved Inspector cannot do this due to omissions and/or known failures of the building work to show compliance with the relevant technical requirements of the Building Regulations, then the relevant local authority should investigate and consider the need to take appropriate enforcement action.