You can only claim expenses that were not covered by health insurance - expenses that you actually paid yourself and for which you did not receive any reimbursement. Also, on your 2017 tax return you can only claim expenses that you actually paid in 2017, no matter when the medical care was provided. If there are some expenses that you did not pay until January, those will go on your 2018 tax return, even though you paid for care that was provided in 2017.