Last year, I took out a loan for $20k for medical expenses. Can this be written off?

[Phillip1 · Accepted solution]

Yes.

IRS Publication 502 states the following about financed medical expenses: 

" If you use a credit card, include medical expenses you charge to your credit card in the year the charge is made, not when you actually pay the amount charged."

If the loan proceeds were used to pay off your medical expense during the tax year, your medical expenses are considered as being paid in the current tax year.