IIRC, in England, the PR 2AR provisions don't make any reference to UC (and nor do/did the DS regs).
It's possible that a few of the local schemes that retain 2AR have been updated re UC but I can't think of any.
That's consistent with CitA's information…
https://www.citizensadvice.org.uk/benefits/help-if-on-a-low-income/help-with-your-council-tax-council-tax-reduction/council-tax-reduction-and-second-adult-rebate/
( I think it's the same position in Scotland and there is no 2AR in Wales ).
