There is no maximum amount of medical expenses you can claim. However, the medical expense tax credit is a non-refundable tax credit. You can use it to reduce the tax that you may have to pay, but it will not add or create a refund. So, if you have a lot of medical expenses, you may not be able to use all of them on your tax return for this year. But you may be able to claim some or all of the unused expenses next year.