Benenden Health Cash Plan: Not-For-Profit Mutual

Assalaam 'alaikum,

Can one of the respected muftis please provide a fatwa with regards to the permissibility of joining a health cash plan like the one provided by Benendens (Health Cash Plans - from £7.65 pm | Benenden Health) which is a not for profit mutual. Any surplus funds generated are reinvested back into the Benenden Health community.

JazakAllah Khair