According to IRS regulations, if a doctor prescribes use of a special type of mattress to treat a specific medical condition, then with the doctor's prescription as documentation to support the expense, the expense would be reimbursable. The IRS does impose certain restrictions on such reimbursement. For instance, the IRS limits the amount of reimbursement to the amount that the special mattress costs over and above a regular mattress. There are different ways to determine this amount, the simplest of which would probably be comparing the cost of the special mattress against a standard brand-name mattress of similar size.
The IRS also limits an item of this type to use by the participant needing the special assistance. Therefore, hypothetically, if two people were going to share a bed, theoretically only half of the cost of the bed would be reimbursable.
You can see from this explanation that this type of expense depends greatly on facts and circumstances of the specific situation. We are available to further discuss the situation, and we will assist in every way possible to ensure that if you make a claim for such an expense it is processed and addressed as efficiently and accurately as possible, to protect you (in case of subsequent IRS personal audit) and the plan.