It would be possible to restrict the payment to only those who need it by using a progressive taxation system and taxing the basic income. You'd set a tax-free threshold at at least a liveable wage level, so that those who earn nothing additional during the year will be assured of the full basic income (tax free). I'd actually set it really high (such that at least 50% of people won't pay tax - i.e. only the top 40% say would pay tax on their UBI), so that when someone is required to repay part or all of their UBI at the end of the financial year, it will be such a tiny amount compared to their income.