All taxes imposed by sections 77-2001 to 77-2037, unless otherwise herein provided for, shall be due and payable twelve months after the date of the death of the decedent, and interest at the rate specified in section 45-104.01, as such rate may from time to time be adjusted by the Legislature, shall be charged and collected on any unpaid taxes due from the date the same became payable, and in all cases in which the personal representatives or trustees do not pay such tax within twelve months from the death of the decedent, they shall be required to give bond in the form and to the effect prescribed in section 77-2009 for the payment of the tax together with interest. In addition, for failure to file an appropriate proceeding for the determination of the tax within twelve months after the date of the death of the decedent there shall be added to the amount due a penalty of five percent per month or fraction thereof, up to a maximum penalty of twenty-five percent of the unpaid taxes due. The filing of a petition or an application for probate proceedings or the filing of an application under section 77-2018.07 and payment of the tentative tax payment within twelve months of the decedent’s death shall be considered an appropriate proceeding for the determination to avoid a penalty and to stop the accrual of a penalty. In addition, the county court may abate this penalty if good cause is shown for failure to file.