what does the IRS letter say? we do not need amounts.
if you got health insurance thru your employer mistyping the amount on the w-2 should not result in the letter
if you had health insurance (Obamacare/AC) thru the Marketplace - you should have gotten a 1095-A then the iRS is likely looking for form 8962. Market place insurance is not reported on your W-2
forms 1095-B and C are not reported on your return.
some other mistyped numbers would change your refund but without knowing what the letter says and what box has the wrong number, its impossible to say whether an amended return is required.
