15-30-2602. Returns and payment of tax -- penalty and interest -- refunds -- credits -- inflation adjustment. (1) For both resident and nonresident taxpayers, each individual or each married couple not filing a joint return and having a gross income for the tax year of more than the maximum standard deduction for that filing status, as determined in 15-30-2132, is liable for a return to be filed on forms and according to rules that the department may prescribe. The gross income amounts referred to in this subsection (1) must be increased by the personal exemption allowance determined in 15-30-2114 for each additional personal exemption allowance that the taxpayer is entitled to claim for the taxpayer and the taxpayer's spouse under 15-30-2114(3) and (4).

(2) In accordance with instructions set forth by the department, each taxpayer who is married and living with a husband or wife and is required to file a return may, at the taxpayer's option, file a joint return with the husband or wife even though one of the spouses has neither gross income nor deductions. If a joint return is made, the tax must be computed on the aggregate taxable income and, subject to 15-30-2646, the liability with respect to the tax is joint and several. If a joint return has been filed for a tax year, the spouses may not file separate returns after the time for filing the return of either has expired unless the department consents.

(3) If a taxpayer is unable to make the taxpayer's own return, the return must be made by an authorized agent or by a guardian or other person charged with the care of the person or property of the taxpayer.

(4) All taxpayers, including but not limited to those subject to the provisions of 15-30-2502 and 15-30-2512, shall compute the amount of income tax payable and shall, on or before the date required by this chapter for filing a return, pay to the department any balance of income tax remaining unpaid after crediting the amount withheld, as provided by 15-30-2502, and any payment made by reason of an estimated tax return provided for in 15-30-2512. However, the tax computed must be greater by $1 than the amount withheld and paid by estimated return as provided in this chapter. If the amount of tax withheld and the payment of estimated tax exceed by more than $1 the amount of income tax as computed, the taxpayer is entitled to a refund of the excess.

(5) If the department determines that the amount of tax due is greater than the amount of tax computed by the taxpayer on the return, the department shall mail a notice to the taxpayer as provided in 15-30-2642 of the additional tax proposed to be assessed, including penalty and interest as provided in 15-1-216.

(6) Individual income tax forms distributed by the department for each tax year must contain instructions and tables based on the adjusted base year structure for that tax year.