“This is a very regressive proposal because it means that the more you earn, the more you benefit,” he said. “You shouldn’t be benefiting the small number of workers who earn more than $50,000 or $60,000 a year. You should be thinking about benefiting the low-income earners who earn maybe $20,000 or $30,000 a year.”

It’s also hard to predict how potential tippers would react to learning that workers who receive tips are exempt from income taxes. The Tax Foundation, a conservative-leaning think tank, has considered the possibility that some employers would find it more lucrative to switch to tips. In theory, lawmakers could pass a provision ensuring that highly paid workers such as lawyers or doctors don’t start receiving part of their income as voluntary tips, but none of the measures currently being introduced in Congress contain such guardrails.

In addition, Gleckman worried that tips would be reduced for employees who receive tips, citing the example of a warehouse worker who visits a restaurant. If the warehouse worker knows that he makes about the same amount as his waiter, but the waiter doesn’t pay the same income taxes, he may be less inclined to leave a generous tip at the end of a meal.