A criterion that determines whether meals eaten alone while working are tax deductible. To be considered a tax-deductible business expense, meals eaten alone must be eaten when the person is doing business away from home for long enough and/or far away enough that an overnight stay is required.

For example, if Zoe drives across town for a business meeting, then stops at a restaurant afterward for a meal, the meal will not be tax deductible because she dined in the general vicinity of her office. She did not stay overnight anywhere, so the expense does not meet the overnight sleep test. If Zoe's office is in Los Angeles and she flies to Denver for a business meeting, then has lunch at the airport and returns to Los Angeles the same day, the lunch is still not tax deductible.