Incidental expenses are minor expenses incurred when conducting business or traveling for work. They include things like fees and tips associated with transportation, lodging and dining.

In the context of travel and business, incidental costs (or "incidentals") are minor, secondary expenses that occur as a result of a primary activity but are not part of the main cost. Common examples include tips for hotel staff (porters, housekeepers), valet parking fees, tolls, and laundry services. For business travelers, incidentals might also include small fees for Wi-Fi, photocopying, or bottled water from a mini-bar. When staying at a hotel, you are often asked for a credit card "hold for incidentals," which acts as a security deposit to cover these potential extra charges. Unlike major costs like airfare or room rates, incidentals are often unplanned or variable. For tax and reimbursement purposes, many organizations use a "per diem" rate—a fixed daily allowance—to cover these small, hard-to-track expenses without requiring a mountain of individual receipts for every small tip given.