Nonaccountable plan is a reimbursement or expense allowance arrangement between an employer and an employee, like an accountable plan's per diem reimbursement, except it does not meet one or more of the three rules listed under accountable plans. In addition, even if an airline pilot or flight attendant’s employer has an accountable plan, the following payments will be treated as being paid under a nonaccountable plan:

• Excess reimbursements the airline employee fails to return to his or her aviation employer, and

• Reimbursement of nondeductible expenses related to the airline pilot or flight attendant's aviation employer’s business.

An arrangement that repays pilots and flight attendants for aviation-related employee business expenses by reducing the amount reported their wages, salary, or other pay will be treated as a nonaccountable plan.