Medical payments are deductible on the date you pay the provider. If you have been paying the provider, let's say $50 per month, then your 2019 deductible amount is the amount you paid to the provider. If you paid the provider in full from a credit card, bank loan, or other payment arrangement, then the provider was paid in full and you can deduct t the entire amount, even though you are making payments to the lender or credit card. (Your payments to the lender are never deductible medical expenses.)
