The 1099-K that is issued every year will not match your Sales (Profit and Loss) report in ScanPower, or your Payment Reports in Seller Central. This is because Amazon uses Gross Sales figures as opposed to Payments figures in the 1099-K.
For example, Shipping credits, Gift Wrap credits, and Promotional Rebates are credited as part of some FBA sales but are then debited before the transaction is posted. Although you, the seller, never see these funds, the gross income figures will include numbers like these. This will cause your total income to appear inflated.
It is up to you or your accountant to determine how much of this excess to categorize accordingly.