Until the rules change ie on 15th May 2019, no 'mixed age' couples have to claim Universal Credit.
Someone of Pension Credit age can make new claims for Pension Credit, Housing Benefit and/or Working Tax Credit - even where they have a partner of working age.
Although many 'mixed age' couples are being wrongly told that they have to claim Universal Credit.
At the moment any 'mixed age' couple should not be refused Pension Credit, Housing Benefit of Tax Credits - if they are being told they cannot claim then they should seek advice immediately.
If a mixed age couple has been told to claim UC, then they should check to see if this is their best option. Most 'mixed age' couples are better off on the legacy benefit system, but some can be better off on UC.
If a mixed age couple is on Universal Credit they can, if they wish, end their UC claim and claim Pension Credit and Housing Benefit instead - click here
Find out more about which 'mixed age' couples are better off / worse off on Universal Credit here