Nancy, a single taxpayer paid $18,000 in medical expenses in 2016. Her AGI in 2016 was $100,000. Nancy filed a claim for reimbursement of medical expenses with her insurance company in 2016 but did not receive reimbursement until May 15, 2017. Nancy paid no other expenses in 2016.

Assuming medical expenses have a 10% floor and the standard deduction in 2016 is $6,300, how much of the medical expense reimbursement must Nancy include in gross in 2017 if she receives a reimbursement of $18,000? Explain your answer.