The UBI and the Longer Working Week

I'm really interested in demographic aging and society is getting older. I think by 2050, we're going to have more people over 65 than under 14. The UBI as well could view it as sort of contributions to pensions because we have a massive shortfall in private pensions. We should be trying to reach out to these desires and demands from people. A logistical question though, because obviously this all sounds wonderful. How does a UBI deal with inflation? Is it simply indexing to CPI or goes on like a pension?