Council Tax
Material Increase in Value and Subsequent Sale
If you materially increase the value of your dwelling by an amount sufficient that it would place the property in a higher band, for example by extending or carrying out other works to your property, the Assessor has a legal duty to increase the banding of the property.
In line with relevant legislation, the change of Council Tax band will only take place if the dwelling is subsequently sold, and will be effective from the date of sale.