To enter meals as an unreimbursed employee expense on Form 2106:
Per IRS Publication 17 Your Federal Income Tax (For Individuals), page 140:
Meals and Incidental Expenses
You can deduct the cost of non-entertainment-related meals if it is necessary for you to stop for substantial sleep or rest to properly perform your duties while traveling away from home on business.
The elimination of the deduction for entertainment expenses is discussed under Meals and Entertainment Expenses, later. The following discussion deals with meals (and incidental expenses).
50% limit on meals. You can figure your meals expense using either of the following methods.
Standard meal allowance. Generally, you can use the “standard meal allowance” method as an alternative to the actual cost method. It allows you to use a set amount for your daily meals and incidental expenses (M&IE), instead of keeping records of your actual costs. The set amount varies depending on where and when you travel. In this chapter, “standard meal allowance” refers to the federal rate for M&IE, discussed later under Amount of standard meal allowance. If you use the standard meal allowance, you still must keep records to prove the time, place, and business purpose of your travel. See Recordkeeping, later.
Special rate for transportation workers. You can use a special standard meal allowance if you work in the transportation industry. You are in the transportation industry if your work:
For additional information please refer to IRS Publication 334 Tax Guide for Small Business or IRS Publication 463 Travel, Entertainment, Gift, and Car Expenses.