In general that's just the same thing. If the per capita average cost of providing roads and schools etc. is $15,000/year then anybody you're taxing less than $15,000/year is really getting a subsidy in the amount of the difference. They get roads and schools and pay less in tax than they cost and the other taxpayers have to pick up the tab.

Nothing about that changes at the point where the amount of "tax" someone pays goes negative. They started getting a subsidy from other taxpayers when they paid less than $15,000, not when they paid less than $0.

So if you want to call a UBI a "tax credit" then go ahead, but changing the name to "tax credit" makes no mathematical or economic difference at all.