They don't seem to have taken into account the increase in people seeking employment, or just extra hours, and the increase in productivity.
And the impact on GDP.
Eg, with more support I wouldn't have taken early retirement on health grounds. I planned to work for at least 4 more years. Paying £1,000+ in taxes every month.
I know lots of others who'd prefer to be working, but without appropriate treatment they can't.
So often analysts miss the whole picture, only considering part of the impact of policies.