Alimony, spousal support, spousal maintenance, or domestic partner support (collectively, spousal support) is generally financial support in the form of periodic payments (usually monthly) paid by one spouse or domestic partner to the other spouse or domestic partner (referred to as spouses) upon divorce. Financial support paid by one spouse to the other spouse while the divorce is pending is often called temporary support.

The law regarding eligibility for spousal support—including the number of years payments must be made and the amount of the payments—often depends on factors such as the length of the marriage, the spouses’ relative earning capacities, the dependent spouse’s education and employment skills, the time a dependent spouse needs to obtain sufficient education or training, and whether there was family violence in the marriage.

Spousal support payments are generally taxable income to the person receiving the payments and deductible for the person making the payments. Such payments generally terminate upon (1) the end of the court-ordered award or payment period; (2) the death of either spouse; or (3) the remarriage of the spouse receiving the payments. And in some states the court may terminate the payments if the spouse receiving payments cohabits (lives) with another person with whom they have a romantic relationship.

Spousal support laws vary from state to state and are generally located in a state’s statutes—often in the family or domestic relations code.

In Montana, spousal support, also known as alimony, is financial assistance provided by one spouse to the other during or after a divorce. The state's laws regarding alimony are found in the Montana Code Annotated (MCA), particularly in Title 40, which pertains to family law. The court considers several factors when determining eligibility for spousal support, including the duration of the marriage, the financial resources and needs of each party, the age and health of the spouses, and the ability of the receiving spouse to become self-sufficient through employment or further education. Temporary support may be granted while the divorce is pending. In Montana, alimony payments are typically considered taxable income for the recipient and tax-deductible for the payer, in line with federal tax laws. However, changes to federal tax law in 2019 mean that for divorce agreements executed after December 31, 2018, alimony payments are no longer deductible for the payer and are not considered taxable income for the recipient. Alimony generally terminates upon the death of either spouse, the remarriage of the recipient, or as ordered by the court, which may include cohabitation in some circumstances.