N.H. Rev. Stat. Ann. § 77-A:10

Each taxpayer shall report to the commissioner of revenue administration any change in the amount of its gross business profits as finally determined by the United States Internal Revenue Service with respect to any previous year for which the taxpayer has made a return under this chapter. Such a report shall be made not later than 6 months after the taxpayer has received notice from the United States Internal Revenue Service that such change has finally been determined. Notwithstanding any other provision of law, a taxpayer reporting a correction pursuant to this section shall be given notice by the department within 6 months of the filing of the report that the return is being reviewed.