45 CFR § 156.1210 - Dispute submission.
(a) Responses to reports. Within 90 calendar days of the date of a payment and collections report from HHS, the issuer must, in a form and manner specified by HHS or the State Exchange describe to HHS or the State Exchange (as applicable) any inaccuracies it identifies in the report.
(b) Inaccuracies identified after 90-day period. With respect to an inaccuracy described under paragraph (a) of this section that is identified and submitted to HHS or the State Exchange (as applicable) by the issuer after the end of the 90-day period described in such paragraph, HHS will consider and work with the issuer or the State Exchange (as applicable) to resolve the inaccuracy so long as—
(1) The issuer promptly notifies HHS or the State Exchange (as applicable) upon identifying the inaccuracy, but in no case later than 15 calendar days after identifying the inaccuracy; and
(2) The failure to identify the inaccuracy and submit it to HHS or the State Exchange (as applicable) in a timely manner was not unreasonable or due to the issuer's misconduct or negligence.
(c) Deadline for describing inaccuracies. To be eligible for resolution under paragraph (b) of this section, an issuer must describe all inaccuracies identified in a payment and collections report before the end of the 3-year period beginning at the end of the plan year to which the inaccuracy relates. For plan years 2015 through 2019, to be eligible for resolution under paragraph (b) of this section, an issuer must describe all inaccuracies identified in a payment and collections report before January 1, 2024. If a payment error is discovered after the timeframe set forth in this paragraph (c), the issuer must notify HHS, the State Exchange, or State-based Exchanges on the Federal platform (SBE-FP) (as applicable) and repay any overpayments to HHS.
(d) Confirmation of HHS payment and collections reports. At the end of each payment year, the issuer must, in a form and manner specified by HHS, confirm to HHS that the amounts identified in the most recent payment and collections report for the coverage year accurately reflect applicable payments owed by the issuer to the Federal Government and the payments owed to the issuer by the Federal Government, or that the issuer has disputed any identified inaccuracies.