Transitional Business Rates relief
If the rateable value of your property changes significantly as a result of revaluation, your rates will change gradually. This is called 'transitional relief'. After each revaluation there is a period of transition. No bill is allowed to increase or decrease by more than a set percentage. Any property with a large increase or decrease in its rateable value will come under the transitional relief scheme, which has the effect of phasing the valuation in over a period of time. If transitional relief applies to your rates bill, it will be applied automatically.
See business rates relief on GOV.UK for details of rate increase limits and rate decrease limits.