It's worth noting that Left-wing UBI can still be seen as a mechanism to replace social safety programs. It just requires that disability payments, etc be merged with the UBI system such that added disability needs can be treated like additional tax credits that get applied to the fixed-interval interest-free loan disbursement from the government based on your taxes that UBI effectively is.

In such a system you get your base UBI tax credit which pushes your tax burden into the negative. Additional UBI-elligible tax credits can push that tax burden even further negative. You can file the paperwork to adjust this at any point in the year and if it's for the current year the tax credit is prorated relative to the date of the next disbursement date (and the full amount for the next year).

Then your UBI disbursement updates and you get it. It works the same way as updating your W-4 tax withholding for a standard W-2 position.

At the end of the year of course your taxes all need to zero out still and if not you either get a bill or a refund.

And this also moves all of the social safety program fraud prevention together into the same system within your tax agency (IRS for the US, or state/local agency, or whatever else).

So instead of a bunch of different agencies and systems for avoiding and finding fraud it all rolls together into the responsibility of the IRS tax assessors, auditors, and the IRS Criminal Investigation unit. And while the rich hate the IRS and common media frames them as incompetent, the people at the IRS are in general extremely competent and more than willing to help and accommodate your average person (less so for the rich who get caught systematically trying to defraud the IRS).