Canada

I'm talking about various social benefits like welfare or disability that would ideally be replaced by a UBI.

I hear a lot of stories about this but I don't remember if they're Canadian or not; There's a lot of people who are on disability and are still capable of doing part time work or taking care of their kids for an hour every day for example, but they can't because if they're found doing anything, they lose all of their disability benefits. We want a system that allows them to do what they can and be rewarded for contributing to the best of their abilities rather than punishing them for it.

It's the same deal with welfare. You need to hit a certain income threshold before your take-home income surpasses what you'd get through welfare. Until then, you're putting a bunch of energy into working to make less money when you could be lounging at home and making more. This actively discourages people from bettering their lives.

I haven't seen any numbers either for or against it, so I can't say anything about viability. If anyone knows enough to run the numbers, I'd like to see it. The problem with the calculations you show above is that you assume the value of money doesn’t change when the world around it changes, but it does. Especially so if you make a large change like implementing UBI. We need to think about this in terms of resources. The question you should be asking is whether there's enough food / housing / labour within the country to fulfill everyone's basic needs.

This assumes that people wouldn't take the same job for less pay if they were guaranteed a fixed amount that more or less made up the difference. If I work a job where I make $50,000/year, and I went to a world where I made $20,000/year UBI and $30,000/ year from my job, I could end up ahead under this scheme with the only additional cost to the economy being my possibly lowered taxes. Under this plan, raising taxes and lowering minimum wage/wage expectations means there would be at most a slight change to corporate taxes (and some jobs would have to pay more when you factor in UBI because desperation would be less of a factor for what people are willing to put up with).

So, realistically, the only cost would be whatever is required to get whoever is below the set line up to the set line, for individuals, corporations, and the government. This would also depend on people who are already making more than UBI to take a "pay cut", and for corporations to not resist paying more taxes to balance the lower payroll costs. So it's never really going to happen.