Checked Council Tax Band and have been made aware of an indicator "Yes" on my address.

Nat111

Please can you help?

I am in England and have been on the webpage Check Council Tax Band Property and have been made aware of an indicator on my address.

It states :

Improvement Indicator “Yes”.

Effect from (is left blank)

I am aware that if a property has been improved or extended since it was placed in a Council Tax band, a Yes will be shown. If a Yes is shown, the band will be reviewed and may increase following the sale of the property. No other propertys with kitchen extensions have the "Yes"  indicator so I assume it is to do with the 2015 Rear Dormer that was never started.

Question 1) How can I find out what date it was added ?

Question 2) Can I have the indicator changed to "No" if it is related to the 2015 Rear Dormer application, and how can this be done? 2019 we had a raised subfloor completed in case we ever changed our mind and resubmitted the plan again ( there is a hefty fee for doing this so we won't ever bother), added a window during a reroof and a hatch with loft ladder, We now have a clean room used for storage. A future sale of the property is pending.

2003 we submitted plans and had a tiny kitchen extension/Conservatory ( 2 x 2.5 metre kitchen plus a 3.5 x 3.5 metre conservatory) completion certificate provided so I don't think it is due to this

Thank you for your time.