I have medicare. I didn't make that clear on my tax form and Turbo figured I should pay $72. per month for 2017. How do I correct this problem?

Medicare is considered acceptable coverage under the Affordable Care Act.

Therefore, when completing the Health Insurance section, you should first indicate that you had coverage the entire year (if this was the case).  The next question will ask if you were enrolled in a Marketplace plan, Medicare is not sold through the Marketplace, therefore, you should indicate No.

Here are the steps to get back to the health insurance section in TurboTax:

• Sign into your account and click Take me to my return
• Use Search (upper right of program) and search health insurance
• Click the Jump to health insurance link from results
• Change your answers as applicable 

Click on screenshot below for details

If you need additional assistance, please comment and I will research further.