The band for your property is shown on your council tax bill. You can also check your banding on GOV.UK: Find your council tax band (GOV.UK)
The Valuation Office allocates your home to one of eight bands according to its open market capital value on 1 April 1991.
If your property was built after 1 April 1991, it would be subject to the same valuation criteria and assessed using 1991 values. Please note: a change in the value of your house caused by general house prices going up or down will not be a reason for changing your council tax band
If your enquiry is about the council tax band given to your property, you need to contact the Valuation Office Agency. Please note, it can currently take up to 12 months for a banding review.