In the UK, a UBI that replaces all other means-tested benefits would increase poverty rates for children, pensioners, and the working-age adults.
Specifically, child poverty could increase anywhere between 5.8% - 10.4% depending on program design. Pensioner poverty could increase between 3.9% to 16.8%. Working class poverty could increase o.4% to 2.8%. In all cases, these rises in poverty rates are the result of the UBI providing less benefit payments than the programs it replaces.