Would the initial 1000$ UBI be paid by the state or by the employer? Assuming that the employee is above threshold. What about the person currently working par

Would the initial 1000$ UBI be paid by the state or by the employer? Assuming that the employee is above threshold. What about the person currently working part-time for $500? It seems like it wouldn't make any material change for them as it would be swallowed by UBI.