How to Calculate Spousal Support in California: Formula and Duration

To calculate spousal support in California, you need to know which stage of the case you’re in. While the divorce is pending, courts use a formula: 40% of the higher earner’s net monthly income minus 50% of the lower earner’s net monthly income. After the divorce is finalized, the formula disappears and a judge sets long-term support by weighing the factors in Family Code Section 4320.¹

The Temporary Support Formula

Temporary spousal support covers the period between filing and the final judgment. Its purpose is to keep the lower-earning spouse financially stable while the case moves through the court. Most California courts run the numbers through a software program called DissoMaster, but the underlying math is straightforward.¹

Start with 40% of the higher earner’s net monthly income.
Subtract 50% of the lower earner’s net monthly income.
The difference is the monthly temporary support payment.

Say one spouse nets $6,000 a month and the other nets $4,000. Forty percent of $6,000 is $2,400. Fifty percent of $4,000 is $2,000. Temporary support comes out to $400 per month.¹

One sequencing point matters. If there are children, child support is calculated first. Child support reduces the paying spouse’s net disposable income, and that reduced figure is what feeds into the spousal support formula. Reversing the order changes the answer.

Judges can deviate from the formula when the circumstances call for it, but the DissoMaster output is where nearly every courtroom starts.

Long-Term Support: Section 4320 Factors

Once the divorce is final, the temporary order is replaced with a long-term (sometimes called “permanent”) order. No formula applies here. The judge looks at both spouses’ full circumstances using the checklist in Family Code Section 4320.²

The factors that tend to drive the number:³

Each spouse’s earning capacity, including whether the supported spouse’s career was set back by time spent on domestic responsibilities.
The supporting spouse’s ability to pay, based on income, assets, and earning capacity.
The marital standard of living, which the court tries to approximate for both parties after divorce.
The length of the marriage.
Each spouse’s needs, measured against that marital standard.
Age and health of both parties.
Contributions one spouse made to the other’s education, training, or career.
Documented history of domestic violence.
Immediate tax consequences to each party.
Separate property, debts, and other financial obligations.
Whether caring for dependent children limits the supported spouse’s ability to work.

No single factor decides the outcome. Two divorces with identical incomes can produce very different orders depending on how long the marriage lasted, what each spouse’s health looks like, and how the property was divided.

When there’s a real dispute about what the supported spouse can earn, either side can ask the court to order a vocational examination under Family Code Section 4331. A qualified evaluator assesses age, health, education, work history, and the local job market, then produces a written report on realistic earning potential and how long retraining might take.⁴ Courts lean on these reports heavily when setting both amount and duration.

California also expects supported spouses to work toward self-sufficiency. Under Family Code Section 4330(b), the court can issue a “Gavron warning” advising the supported spouse to make reasonable efforts to provide for their own needs.⁵ Ignoring that warning can lead to a reduction or termination at a later modification hearing. For long marriages, or where the supported spouse is elderly or seriously ill, the judge can decide the warning isn’t appropriate.

How Long Support Lasts

The length of the marriage is the biggest factor in duration, and California draws a line at ten years.

For marriages under ten years, support generally runs for half the length of the marriage. A six-year marriage typically produces a three-year support order.²
For marriages of ten years or more, the court retains jurisdiction indefinitely. That does not guarantee lifetime payments; it means the court keeps authority to extend, reduce, or terminate support as circumstances change.⁶

A marriage slightly under ten years isn’t automatically excluded from indefinite jurisdiction. Section 4336 allows the court to find that a shorter marriage qualifies as “long duration” based on the circumstances, though that’s unusual.⁶

When Support Ends Automatically

Unless the parties agreed otherwise in writing, spousal support terminates by operation of law when either spouse dies or when the supported spouse remarries. No filing is needed.⁷

Cohabitation works differently. If the supported spouse begins living with a new romantic partner, support does not end automatically, but the law creates a rebuttable presumption that their need has decreased. The paying spouse can then file a motion to reduce or terminate support, and the burden shifts to the supported spouse to prove ongoing need at the same level.⁸ The supported spouse doesn’t need to be holding themselves out as married for the statute to apply.

Federal Tax Treatment

The tax treatment of spousal support at the federal level depends on when the divorce or separation agreement was signed. The Tax Cuts and Jobs Act of 2017 flipped the rules for agreements executed after December 31, 2018:⁹

For agreements executed before 2019, the paying spouse deducts support from taxable income and the receiving spouse reports it as income.
For agreements executed after 2018, the paying spouse gets no deduction and the receiving spouse owes no federal income tax on the support.

If a pre-2019 order is later modified, the old rules keep applying unless the modification specifically adopts the new treatment. This matters for the calculation itself, because tax consequences are one of the Section 4320 factors judges weigh. Post-2018, the paying spouse absorbs the tax on income used to make the payment, which can affect the amount the court orders.³

Changing the Amount Later

Support orders are not fixed. Either spouse can ask the court to modify the amount or duration by showing a material change in circumstances since the last order.¹⁰ The changes that typically justify modification include:

A significant increase or decrease in either spouse’s income.
Job loss or an involuntary reduction in hours.
Retirement of the paying spouse, especially at a customary retirement age.
Serious health problems affecting ability to work or need for support.
The supported spouse becoming self-sufficient, or failing to make efforts toward self-sufficiency after a Gavron warning.

You request a change by filing a Request for Order (Form FL-300) with the court that issued the original order. The filing fee for a family law motion in California is $60 as of 2026.¹¹

There is one major exception. If both spouses agreed in writing that support is non-modifiable, the court cannot later change the amount or duration regardless of what changes. That kind of clause sometimes appears in marital settlement agreements when one spouse accepts a higher amount in exchange for the other giving up future reductions. Think carefully before agreeing to it, because a drop in your income won’t unlock any relief.

Some agreements include a cost-of-living adjustment clause that raises the payment each year based on an inflation index. Without a COLA clause, the only way to bump support for inflation is to file a modification motion and prove changed circumstances.

1
California Courts | Self Help Guide. Temporary Spousal Support
2
Judicial Branch of California. Long-term Spousal Support
3
Justia. California Family Code 4320-4325
4
California Legislative Information. California Family Code 4331
5
California Legislative Information. California Family Code 4330
6
California Legislative Information. California Family Code 4336
7
California Legislative Information. California Family Code 4337
8
California Legislative Information. California Family Code 4323
9
Internal Revenue Service. Topic No. 452, Alimony and Separate Maintenance
10
Judicial Branch of California. Ask to Change Your Long-term Spousal Support Order
11
Superior Court of California. Statewide Civil Fee Schedule Effective 01-01-2026