'Salary' from an employer to the assessee is taxable as per section 15 of Income tax Act.
Now, as per section 17(1), 'salary' includes perquisites.
Perquisite as per clause (vi) of section 17(2) includes the value of any other fringe benefit or amenity as may be prescribed. But the proviso to that clause says nothing in that clause is applicable to any sum paid by the employer in respect of reimbursement of medical expenses if the sum does not exceed Rs 15000.
Therefore, as long as the reimbursement doesnot exceed Rs 15000, it is not salary and therefore need not be included in the salary itself. But, if the reimbursement exceeds Rs 15000, then the amount has to be included as salary and deduction to the extent of Rs 15000 has to be shown separately in Form 16.