Ken Cherry was advised by his doctor to swim to relieve symptoms of severe emphysema and arthritis. He built a new house with an indoor pool, which he used regularly; his condition improved. Cherry deducted $4,000 for the operating costs of the pool. The IRS scoffed, but Tax Court allowed the deduction, in part because his family rarely used the pool, according to J.K. Lasser’s Your Income Tax 2011. In some cases pools may be partially deductible as a medical expense. The IRS has denied the deduction for other taxpayers, however, when medical necessity wasn’t so clear. So forget about the waterslide deduction.