Fair Playing Field Act of 2010 - Amends the Internal Revenue Code, with respect to the classification of workers for employment tax purposes, to: (1) repeal the prohibition against issuance of regulations and guidance by the Secretary of the Treasury on workers' employment tax status (i.e., as an employee or as an independent contractor) enacted by the Revenue Act of 1978; (2) direct the Secretary to issue regulations and other guidance to clarify the proper employment status of workers for employment tax purposes; (3) prohibit a retroactive assessment of employment tax, except with respect to certain skilled workers, for tax periods after December 31, 1978, and before a specified reclassification date for worker misclassifications, unless the taxpayer had no reasonable basis for not treating a worker as an employee; (4) require taxpayers who hire independent contractors on a regular and ongoing basis to provide such contractors with notice of their federal tax obligations, the labor and employment law protections that do not apply to them, and their right to seek a status determination from the Internal Revenue Service (IRS); and (5) eliminate reduced penalty provisions for failure to withhold income taxes for taxpayers who lack a reasonable basis for treating a worker as other than an employee (i.e., as an independent contractor).