Revenue Service Independent Office of Appeals to appeal the proposed assessment of such payment before issuing the notice and demand for payment under paragraph (1). . (b) Effective date The amendment made by this section shall apply to assessments in taxable years beginning after the date of the enactment of this Act. 7. Statute of limitations on penalty assessment (a) In general Section 4980H(d) of the Internal Revenue Code of 1986, as amended by section 6, is amended by adding at the end the following new paragraph: (5) Statute of limitations on penalty assessment With respect to an assessment of an assessable payment under paragraph (1), the statutory period for such assessment shall expire at the end of the 3-year period beginning on the date the employer files the return under section 6056 for the calendar year with respect to which such payment is determined. . (b) Effective date The amendment made by this section shall apply to proposed assessments with respect to which a letter described in section 4980H(d)(4) of the Internal Revenue Code of 1986 (as added by this section) is issued in taxable years beginning after the date which is 1 year after the date of the enactment of this Act. 8. GAO studies (a) Study of first years of employer reporting (1) In general The Comptroller General of the United States shall conduct a study that evaluates, with respect to the period beginning on January 1, 2015, and ending on December 31, 2022— (A) the notification of employers by Exchanges established under title I of the Patient Protection and Affordable Care Act ( Public Law 111–148 ) that a full-time employee of the employer has been determined eligible for advance payment of premium tax credits under section 36B of the Internal Revenue Code of 1986 or cost-sharing subsidies under section 1402 of such Act ( 42 U.S.C. 18071 ), including information regarding— (i) the data elements included in the employer notification