There's a common misconception that when a couple divorces after more than ten years of marriage, there's a rule requiring that alimony be paid indefinitely. In reality, there is no "Ten Year Rule." Here are the facts:
California law (Family Code Section 4336(a)) says that where a marriage is "of long duration," the court "retains jurisdiction" indefinitely after the divorce is completed, unless the spouses agree otherwise. Retaining jurisdiction means that the court has the ability to continue making decisions about matters between the spouses, and can reevaluate its original orders and modify them if the facts justify a change. Any marriage that is longer than ten years is automatically considered to be "of long duration," and sometimes, shorter marriages can be considered lengthy as well.
Example # 1: Jill & Jim were married for 6 years. As part of their divorce, the court orders Jim to pay Jill support in the amount of $500 per month for three years. The order also ends the court's jurisdiction after three years. Therefore, if Jill were to lose her job or get sick during the first three years after the divorce, the court could increase her support. But once the three years have passed, the court cannot modify Jill's spousal support (the court no longer has "jurisdiction" to award spousal support).
Example # 2: Jill & Jim were married for 12 years. She receives the same amount, this time for 6 years. However, because Jill & Jim have been married for more than 10 years, the marriage is considered long-term, and the court will retain jurisdiction to modify this support amount. Under these circumstances, the court may retain jurisdiction indefinitely (until Jill remarries or passes away). Therefore, if Jill got sick the month before her support is to end, she could ask the court to extend the duration of support and even ask for a higher amount of support.
In the examples above, Jill received an award for support for half the length of her marriage. Where the marriage lasted less than ten years, it is quite common for a court to set the duration of support at half the length of marriage, but the court isn't bound to do that. With marriages longer than ten years, the formula may not be followed as commonly, and the court is more likely to weigh the factors listed below to determine the duration of support.
Setting the Duration and Amount of Support (Family Code §4320 Factors)
A California court determines the amount and duration of permanent spousal support by weighing twelve factors set out in Cal. Fam. Code §4320:
(a) The extent to which the earning capacity of each party is sufficient to maintain the standard of living established during the marriage
(b) The extent to which the supported party contributed to the attainment of an education, training, a career position, or a license by the supporting party
(c) The ability to pay of the supporting party, taking into account the supporting party's earning capacity, earned and unearned income, assets, and standard of living
(d) The needs of each party based on the standard of living established during the marriage; (e) The obligations and assets, including the separate property, of each party
(f) The duration of the marriage
(g) The ability of the supported party to engage in gainful employment without unduly interfering with the interests of dependent children in the custody of the party
(h) The age and health of the parties, including, but not limited to, consideration of emotional distress resulting from domestic violence perpetrated against the supported party by the supporting party where the court finds documented evidence of a history of domestic violence, as defined in Section 6211, against the supported party by the supporting party
(i) The immediate and specific tax consequences to each party
(j) The balance of the hardships to each party
(k) The goal that the supported party shall be self-supporting within a reasonable period of time. Except in the case of a marriage of long duration as described in Section 4336, a "reasonable period of time" for purposes of this section generally shall be one-half the length of the marriage. However, nothing in this section is intended to limit the court's discretion to order support for a greater or lesser length of time, based on any of the other factors listed in this section, Section 4336, and the circumstances of the parties; and
(l) Any other factors the court determines are just and equitable.
The judge doesn't have to use the Family Code Section 4320 factors to determine temporary support, so if one spouse is seeking support while the divorce is going on, the judge will likely use a formula set out by the local county to set the amount of temporary support.
In summary, there is no "Ten Year Rule" requiring that support must last indefinitely if the marriage was longer than ten years. However, ten years is an important milestone that may affect the court's ability to revisit the issue of spousal support later.