Should i add form 1099-sa to my prior year return and complete form 8889?

[dmertz]

If you received a Form 1099-SA that you failed to report on the tax return that should have shown that distribution, you must amend that year's tax return and provide a correct Form 8889.  IF you don't, expect the IRS to assume that the distribution was not used for medical expenses and bill for the additional tax, interest and possible late-payment penalty based on that assumption.