If you have medical expenses as fuel for traveling is that just a tax credit or can you actually get more refund than just what you paid in income tax?

You could possibly get a "refund" over and above what you have paid in income tax if you qualify for the Refundable Medical Expense Supplement.  The refundable medical expense supplement is a refundable tax credit available to working individuals with low incomes and high medical expenses. 

Generally, when you claim medical expenses on your tax return, they are a "Non-Refundable Tax Credit". This means that once you reach the minimum amount of expenses required (3% of your net income), the amount over and above that will only be used to reduce your tax payable. 

If you do qualify for this credit, TurboTax will do all the calculating for you. Simply enter your information and let the software do the work. Here's a tax tip on claiming Medical Travel Expenses:

https://bit.ly/2SUrQBv