N.H. Rev. Stat. Ann. § 383-B:8-802

A depository bank may convert into a national bank or federal savings bank. The conversion shall be governed by federal law and not the law of this state, except that the conversions shall be approved by a majority of the holders of each class of voting stock of an investor-owned depository bank, the corporators of a mutual savings bank, or the association members of a savings association, or by a higher percentage if required by the entity's organizational documents.