No, you cannot deduct those expenses on your tax return.
According to IRS Publication 970, you cannot deduct education expenses (including exams and prep courses) if they are part of a program of study that will qualify you for a new trade or business.
Even if your wife has a degree in a related field, the IRS views the exam as the "minimum educational requirement" to become a licensed Occupational Therapist. Because she cannot practice as a licensed OT without passing the exam, the cost of getting it is considered a personal expense, and it is not deductible.
