Incidental expenses are the "I" in M&IE. When a taxpayer deducts employee business expenses from their taxes, typically, the incidental expenses are lumped in with the meal expenses to give the taxpayer the M&IE total. It is possible (even though it is very rare) that a taxpayer can calculate the incidental expenses separate from the meal expenses. In that case, the taxpayer could use the actual costs of the incidental expenses incurred during the tax year. The following travel expenses are considered to be incidental expenses.

• Fees and tips given to porters, baggage carriers, bellhops, hotel maids, stewards or stewardesses and others on ships, and hotel servants in foreign countries,
• Transportation between places of lodging or business and places where meals are taken, if suitable meals can be obtained at the temporary duty site, and
• Mailing costs associated with filing travel vouchers and payment of employer-sponsored charge card billings.  

Incidental expenses do not include expenses for laundry, cleaning and pressing of clothing, lodging taxes, or the costs of telegrams or telephone calls. If an item is NOT listed as and incidental expense AND it is determined to be a tax deductible employee business expense, then the item can be added to your itemized employee business expenses if done properly. On the other hand, if an item IS listed as an incidental expense AND you use the normal M&IE calculation as most people do, DO NOT add that expense into the list of employee business expenses because you are essentially double-dipping. The reason it is considered to be double-dipping is that the expense is already automatically a component of the M&IE total.