All properties which are occupied are subject to council tax banding depending on the value of the property. Bands are from A which is the lowest to H which is the highest. There is a discount of 25% if the property only has one occupier. Further discounts may be available for disabled people.
If you live in the same property as the person you care for but they are not your spouse, partner or a child under 18 you may also qualify for a discount. The rules are complicated but if you are caring for a relative or elderly person for more than 35 hours per week and the person receives high rate of Disabled Living Allowance, High Rate Attendance Allowance, Personal Independence Payment, Increased Disablement Pension or Increased Constant Care Allowance you should be able to make a claim. Remember the benefits system is subject to a review by central government and the amount of one benefit may be reduced if claiming another. Check with your local council or Citizens Advice.