Alaska Stat. § 43.05.260 – Limitation on assessment

(a) Except as provided in (c) of this section, AS 43.20.200(b), and AS 43.55.075, the amount of a tax imposed by this title must be assessed within three years after the return was filed, whether or not a return was filed on or after the date prescribed by law. If the tax is not assessed before the expiration of the applicable period, proceedings may not be instituted in court for the collection of the tax.
(b) For purposes of this section, a return filed before the last day prescribed by law or regulation is considered as filed on the last day.
(c) The following exceptions apply to the limitation period in (a) of this section:
1. (1) in the case of a false or fraudulent return with the intent to evade tax, the tax may be assessed, or a proceeding in court for collection of the tax may be begun without assessment, at any time;
2. (2) in the case of a failure to file a return, the tax may be assessed, or a proceeding in court for the collection of the tax may be begun without assessment, at any time;
3. (3) if, before the expiration of the time prescribed in this section for the assessment of a tax imposed by this title, both the department and the taxpayer have consented in writing to the assessment after the expiration of the time, the tax may be assessed at any time before the expiration of the period agreed upon; however, the period agreed upon may be extended by a subsequent agreement in writing made before the expiration of the period previously agreed upon.