It is up to a landlord to decide who they let their property to. We would encourage all landlords to consider each application on its individual merits.
'DSS' is a defunct term that refers to the Department for Social Security, which hasn't existed since 2001. Within the context of housing, it is understood to refer to tenants who claim any kind of state benefit - especially housing benefit (or Universal Credit).
As such, writing 'No DSS' on an advert is, in a way, meaningless, since no one claims benefits from the Department for Social Security anymore.
The issue is not the wording, but whether the landlord/agent is universally rejecting all applications from tenants who claim benefits.
One line of thought is that advertising 'No DSS' (or similar) constitutes a form of discrimination which may be found to be illegal. For example, women are more likely to be recipients of child care benefits, and so advertising 'No DSS' may be found to indirectly discriminate against women, as described in the Equality Act (2010).
There have been out-of-court settlements where tenants won large sums before the case was tried. In early 2018, Rosie Keogh won £2,000 in private settlement over an advert blanket-banning benefit claimants. Read about it here.
One case went to trail in July 2020. The court declared the policy of an agent to routinely reject all tenants who claim benefits to be unlawful on the grounds described about. The agent declined to make any defence of their policy. You can read the ruling here and some analysis here.
DSS and OpenRent
At OpenRent, we have no public or tacit policies against tenants who claim benefits. We never advise landlords not to select tenants who claim the benefits they are entitled to. We invite landlords to consider all prospective tenants on their individual circumstances and offer tenancy creation support to all landlords, including detailed guidance on how to make tenancies work when tenants fail referencing.
We do allow landlords to list their property as 'Accept DSS Income' so that tenants on benefits are able to quickly identify properties where they will have a great chance of being accepted. This helps tenants waste less time applying to properties which, on other websites, would appear to be available to all, but which a secret 'no DSS' policy would frustrate.
Enquiries from benefit claimants are passed onto landlords even where the landlord has specified they are unable to let to tenants who claim benefits. We are the only letting agent that lets thousands of 'DSS income accepted' properties across the UK every year with no admin or agency fees.