In the olden days, there was a nationally set out benefit called council tax benefit. It was a means tested benefit (the more money you have, the less you get) for people who could not afford to pay their council tax benefit.
So the government abolished it, except for pensioners. Instead each council had to work out its own scheme for people under pension age. It is very hard to find out the rules. So I am publishing them here:
The rules tell you the scheme as it was set out in April 2019
Key points to note:
1) Even the very poorest must pay 20% of their council tax.
2) There are horrible rules for self employed people. You will be assumed to be earning at least a minimum income, even if you are not.