Would the basic income vary for different sectors of the population for example the elderly, the handicapped, immigrants, children...?
As has been stated, the handicapped would receive more if the basic income was insufficient to meet their needs.
Children and the elderly could receive less if it was thought that they have less expenditures.
Immigration is clearly a potential problem but this could be resolved by only granting the basic income to people who have citizenship.
The government needn't perceive the basic income as a loss of revenue as it would increase purchasing power and consumption and this would stimulate economic growth.