A Universal Basic Income in Scotland set at the level of the state pension (which campaigners for years have argued is too little to live on) and paid to all citizens would require £38bn per year. This would be the same as the cost of 3 Scottish NHSes.
To pay for this a range of existing payments could be rolled in. All current social security spending in Scotland adds up to c.£19bn per year (and this includes disability and housing schemes that would be *very* problematic to roll in to a UBI). £19bn more to find.
The next path is raising more revenue. Most UBI schemes therefore involve eliminating the relief that means you pay no income tax on the first £12,500 you earn. Extending NI to all earnings (meaning 12% extra tax on earnings at the bottom, 10% extra on more than £962/week.)
In Scotland doing all that might raise you £12-14bn. So that just leaves £5-7bn per year (barely half an NHS.) To fill the gap you could raise income tax. This would need to be by around 10-12%. Including the merger with NI that means all income taxed at at least 42-44%.
An alternative might be cutting back the generosity. For example, you might only pay children half the amount. That would save £3bn. Or you could reduce the amount paid more generally, though it is already a very basic sum.
You might also embrace heterodox economic approaches such as Modern Monetary Theory. I will say no more on this except that while it has very articulate passionate proponents they remain a small minority within that discipline.
There are also behavioural questions. Going from unemployment into work would not involve losing state payments so could be more attractive. At the same time, going into work when 42-44% of every £1 you would earn is taken in tax could be less so. We don't know.
A small change in work-related incentives either way could result in a very large change in the income tax base that is needed to pay for UBI.
I am deliberately not touching here on the desirability of UBI. I merely want to set out (in a rough and ready way) the practicalities that would be involved. If £132 per week is worth 42-44% tax to all citizens (or MMT) then by all means argue for it.
I'm also aware these are figures thrown together quickly on a Sunday morning. They may be off by a billion here or a billion there (and that's the kind of scale we have to talk about with UBI) but they are going to be in the correct vicinity and are as likely to be over as under.
Finally, this is all based on an ongoing UBI. A one-off, short-term UBI in a time of crisis (i.e. now) is a whole different set of calculations.
TL/DR - a modest UBI would cost about 23% of the entire Scottish economy and you should only advocate it if you also have a way of paying for it that you are comfortable with.
