I was charged $820 with a notice (CP14H) for not securing minimum essential health insurance when I have a 1095-C. How can I dispute the $820 charge?

[DoninGA]

If you and your dependents (if applicable) had employer provided coverage for 2015 and you disagree with the IRS assessment, then contact the IRS using the phone number on the notice.

See this IRS website for a CP14H notice - https://www.irs.gov/individuals/understanding-your-cp14h-notice