The rule that applies now
Band E is the current minimum for letting, subject to the registered exemptions. A property below it cannot lawfully be let without one.
The one that is coming
Band C has been the stated direction for the private rented sector for several years, and the date has moved more than once. We are not printing a countdown to a date that keeps changing, because planning capital works against a moving target is how landlords waste money early or panic late.
What to do with that
Treat band C as the design target for any work you were going to do anyway. Insulation and heating decisions made at a natural point, a boiler failure, a void, a refurbishment, cost a fraction of the same work done under deadline pressure.
Where the data sits
Ratings and expiry dates per property, alongside the rest of the certificates, and EPC expiry counts in the compliance score.