Apart from properties that are exempt from business rates, each non-domestic property has a rateable value which is set by the valuation officers of the Valuation Office Agency (VOA), an agency of Her Majesty’s Revenue and Customs. They draw up and maintain a full list of all rateable values. The rateable value of your property is shown on the front of your bill. This broadly represents the yearly rent the property could have been let for on the open market on a particular date. For the revaluation that came into effect on 1 April 2017, this date was set as 1 April 2015.
The valuation officer may alter the value if circumstances change. The ratepayer (and certain others who have an interest in the property) can request a change to the value shown in the list if they believe it is wrong, through the reformed Check, Challenge, Appeal (CCA) process introduced in April 2017. Your billing authority can only backdate any business rates rebate to the date from which any change to the list is to have effect.