Thank you for clarifying that, that brings about a different result.
If you sold your personal items for less than you paid – which you imply, since you sold for a loss – this should not be reported on your return. So, DON”T REPORT IT. And, since your transactions were below the $20,000 / 200 transaction thresholds of the IRS, the 1099-K issuer is supposed to report the information only to the Commonwealth of Massachusetts, and not to the IRS. So, you shouldn’t be getting any letters from the IRS.
Massachusetts has different reporting requirements for the 1099-K than the IRS -- third party settlement organizations (“TPSOs”) report transactions amounting to $600 or greater, regardless of the number of transactions. When TPSOs have transactions above the Massachusetts threshold but below the federal threshold, they report only to Massachusetts, and not the IRS. See <a rel="nofollow" target="_blank" href="
https://www.mass.gov/service-details/new-massachusetts-reporting-requirements-for-third-party-settle...>.
