IRS is eying businesses that fail to report income shown on 1099-K forms. It compared 1099-Ks filed by credit card companies and third-party networks such as PayPal with income shown on returns by taxpayers who received the forms. It’s now mailing notices to firms it believes may have under-reported gross receipts. But the 1099-K matching program is impressive. The form reports receipts for a calendar year, which doesn’t jibe for firms with fiscal years. And businesses don’t have to separately report amounts shown on 1099-Ks. So the form’s usefulness as a tool to spot under-reporting is lessened. Nevertheless, IRS will still ask businesses to explain discrepancies and will follow up with firms that don’t respond to the notices.