Q. I havent protected my tenancy deposit. I want to evict my tenant now as he is not paying rent. Is this a problem?
A. It depends. If you want to use the section 21 procedure, then you need to protect the deposit AND serve the notice giving required information on the tenant before you serve your section 21 notice. If you dont the notice will be invalid and any claim for possession based on it will fail.
If you want to base your claim on the mandatory rent arrears ground (ground 8) after service of a notice under section 8 of the Housing Act 1988, then strictly speaking, failure to protect the deposit is not an absolute bar (as it is for section 21 claims). However your tenant may seek to derail you claim by putting in a claim for the penalty of three times the tenancy deposit by way of a counterclaim.
So to protect yourself against this I would strongly advise that you protect the deposit before issuing proceedings.