The 1099-K form only reflects gross sales and receipts that you’ve received via PayPal. You may have valid sources of revenue in addition to PayPal, and if so, of course, the IRS will expect you to report that income as well.
If you believe that the 1099-K totals are lower than what your PayPal sales should be, GoDaddy Bookkeeping can help illuminate the transactions being reported. You can quickly drill in to the particular transactions that PayPal has reported for you. Based on that list, you’ll be able to see if transactions are included that don’t belong in these totals.
Remember, the number on the 1099-K is what PayPal reported to the IRS. You are required to claim AT LEAST this much income on your taxes.