N.H. Rev. Stat. Ann. § 281-A:35

Payments made by an employer, or the employer's insurance carrier, to an injured employee during the period of the employee's disability, or to the dependents of such employee, which, by the provisions of this chapter, were not due and payable when made, may, subject to the approval of the commissioner, be deducted from the amount to be paid as compensation; provided that, in a case of disability, such deduction shall be made by shortening the period during which compensation shall be paid and not by reducing the amount of the weekly payments under this chapter.