Haw. Rev. Stat. § 236D-9: Amended returns; final determination.

(a) If an amended federal return is filed, there immediately shall be filed with the department an amended Hawaii report with a true copy of the amended federal return. If an additional tax under this chapter is required to be paid pursuant to the amended return, the person required to pay the tax shall pay the additional tax, together with interest as provided in section 236D-7, at the same time the amended return is filed, subject to any extension election under section 236D-7.

(b) Upon final determination of the federal tax due, the person, within sixty days after the determination, shall give written notice of the determination to the department in such forms as may be prescribed. If any additional tax is due under this chapter by reason of the determination, the person shall pay the tax, together with interest as provided in section 236D-7, at the same time the notice is filed, subject to any extension election under section 236D-7.