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Changing the custody or maintenance set by the judgment

Last updated 2026-09-01 · Reviewed by Jaime Piñeira Pardo, registered with the ICAM bar, no. 138826

The short answer

Simply stopping payment reduces nothing: the judgment stays alive and the debt piles up. What is needed is a claim to modify measures under article 775 of the Ley de Enjuiciamiento Civil before the same Tribunal de Instancia that ordered them, showing that circumstances have substantially changed. There is no lapse period, but the courts' criterion is that effects run from the filing of the claim.

The divorce judgment three years ago set 450 euros a month in child maintenance for two children, calculated on a salary of 2,600 euros. You were dismissed in January and since March you have received a benefit of 1,150 euros. You have been paying 200 euros a month and warning by message, but your former partner does not accept the reduction and tells you she will claim the difference. You assume that, because your situation is obvious and documented, the maintenance adjusts by itself.

The case, in five lines

What is brought: A claim to modify final measures under article 775 of the Ley de Enjuiciamiento Civil, with an application for provisional modification while it is decided.
Before which court: The sección de familia del Tribunal de Instancia (the family section of the first-instance court) that ordered the final measures, as article 775 itself requires.
Deadline: There is no lapse or limitation period: it can be sought while the measures are in force. The cost lies in delay, because the modification looks forward from the filing of the claim and does not erase instalments already due.
Who can bring it: Either spouse, in all cases, and the public prosecutor where there are minor children or children with disabilities whose support measures are entrusted to their parents.
Financial risk: If the substantial change is not proven, the claim is dismissed, the measures remain intact and costs may be awarded against you. While the case lasts, the earlier judgment continues to be enforced unless provisional modification is obtained.

The judgment stays alive until another one changes it

Maintenance set in a judgment does not adjust itself, nor is it suspended because the payer has lost their job. Until another decision modifies it, every instalment falls due and is enforceable in full, and the gap between what was ordered and what was paid is a debt recoverable by enforcement. Sending messages, however well documented the dismissal, has no legal effect at all on the amount.

Article 90.3 of the Código Civil states when it can be changed: the measures the judge adopts absent agreement, or those agreed judicially, may be modified judicially or by a new agreement approved by the judge where the children's new needs or the change in the spouses' circumstances so advise. Article 91 repeats it in a few words: where circumstances change substantially.

There is a route without litigation worth ruling out before suing. Article 90.3 itself accepts that measures agreed before the court clerk or in a public deed may be modified by a new agreement subject to the same requirements of the Código. If the other party accepts the new figure, it is documented and approved; if not, the claim is the only path that produces effects.

What counts as a substantial and supervening change

Article 775.1 of the Ley de Enjuiciamiento Civil requires that the circumstances taken into account when approving or ordering the measures have substantially changed. That is three requirements in one: the change must be later than the judgment, it must be relevant, and it must affect precisely the data on which the disputed figure was calculated. What was already known when judgment was given cannot be used to review it.

For money, the substantive reference is article 146 of the Código Civil: the amount of maintenance is to be proportionate to the means of the person providing it and to the needs of the person receiving it. That double proportion explains why review can come from either side: because the payer's income falls in a lasting way, or because the children's needs change with age, schooling or illness.

That is why the case is won or lost on proof that the change will last. One bad month is not a substantial change, and a fall in income brought about by the person relying on it is not rewarded either. Against that, a dismissal with a recognised benefit, an incapacity, the birth of another child or the genuine independence of an adult child are verifiable facts that support the claim.

No lapse period, but every month you wait is money lost

Article 775 sets no period at all: modification may be sought while the measures are in force, and there is no lapse or limitation period to shut the door. That apparent comfort is the trap of the case, because the settled criterion of the courts is that the new amount applies from the filing of the claim and not from the day the change of circumstances occurred.

The practical consequence is arithmetic. If you were dismissed in January and file in October, the nine intervening months are still owed at the old figure, and that arrears will later be claimed by enforcement with the special rules of article 776. Filing late does not merely delay the reduction: it consolidates a debt that can no longer be argued through a modification claim.

Provisional modification avoids waiting for the judgment

Paragraph three of article 775 allows the parties to request, in the claim or in the defence, the provisional modification of the final measures granted in earlier proceedings, referring for that purpose to article 773. That opens the way to a hearing and a swift order adjusting maintenance or the custody arrangement while the case proceeds, without waiting months for judgment.

The route of the main case is set by paragraph two: these applications follow article 770, that is, the same rules as contested family proceedings, unless the application is made by both parties jointly, or by one with the other's consent and attaching a proposed settlement agreement, in which case the article 777 procedure applies.

Changing custody is measured against the child's best interest

Modifying the custody arrangement is not won with the same material as modifying maintenance. Proving a financial change is not enough here: it must be shown that the new situation, whether a move, a change of working hours, the children's age or the way the current arrangement is being complied with, means the existing system no longer serves the children's interest.

It is also worth separating the two fronts in the pleading. A claim that mixes personal reproach with a custody request weakens itself, while one documenting objective facts, the real care calendar and school performance gives the court a verifiable account. The same claim may seek review of both the arrangement and the maintenance, because a change of custody drags the financial calculation with it.

How we run the case, step by step

1
Comparing the judgment with today's reality
We read the judgment and its reasoning to identify exactly which circumstances were taken into account when each measure was set. Without that comparison there is no way to prove the change is substantial and later, which is what article 775 requires.
2
Documenting the change and that it will last
We gather the dismissal letter, the benefit decision, the employment record, tax returns, medical reports or new school costs. What decides the case is not that you earn less today, but that the change is neither temporary nor brought about by the person relying on it.
3
Trying agreement before suing, without losing time
Article 90.3 allows modification by a new agreement approved by the court. We put a figure in writing with the documents attached and a short deadline to reply, because every month without a claim is a month still owed at the old amount.
4
Modification claim with a provisional application
We file the claim before the same court that issued the measures and include in it the provisional modification of article 775.3, which follows article 773 and allows an immediate adjustment while the case is decided.
5
Hearing, evidence and judgment with effect from the claim
The case follows article 770, with compulsory personal attendance and the children heard where appropriate. The judgment replaces the earlier measure and takes effect from the filing of the claim, not from when the change occurred.

The evidence that decides the case

The complete earlier judgment, with the reasoning that records the salary, the division of time and the needs on which the calculation was based.
The dismissal letter or termination, together with the decision recognising the benefit and its exact amount and duration.
The employment record and tax returns for recent years, which show whether the fall in income is a dip or a sustained line.
The children's current costs evidenced by invoices: school, meals, activities, medical treatment or new needs arising from their age.
Bank receipts for every transfer made since the judgment, which fix exactly what has been paid and what is owed.
The care calendar actually complied with over the past year, contrasted with the one set by the judgment, where the request is to change custody.

What closes the door

Stopping payment and waiting for someone to understand. Maintenance remains owed in full until another decision modifies it, and non payment builds a debt recovered by enforcement.
Delaying the claim while negotiating by message. Because modification runs from the filing of the claim, every month of conversation is a month still owed at the old amount.
Relying as a new circumstance on something that already existed when judgment was given. Article 775 requires a change in the circumstances taken into account when the measures were ordered, not a different reading of the same ones.
Causing your own drop in income, by resigning or changing activity without financial explanation. The court assesses the payer's conduct, and a self induced reduction does not support the review.
Filing the claim without seeking the provisional modification of article 775.3, and sustaining throughout the case an amount you can no longer pay.

The law that applies

Art. 775 LEC. Allows the public prosecutor, where there are minor children or children with disabilities whose support measures are entrusted to their parents, and in all cases the spouses, to ask the court that ordered the final measures to modify them provided the circumstances taken into account when approving or ordering them have substantially changed. Its third paragraph allows provisional modification to be sought in the claim or the defence. BOE-A-2000-323
Art. 90.3 CC. Measures adopted by the judge absent agreement, or agreed judicially, may be modified judicially or by a new agreement approved by the judge where the children's new needs or the change in the spouses' circumstances so advise, and those agreed before the court clerk or in a public deed may be modified by a new agreement subject to the same requirements. BOE-A-1889-4763
Art. 91 CC. In judgments of nullity, separation or divorce the court determines, absent agreement, the measures on the children, the family home, pets, the burdens of the marriage, the liquidation of the property regime and the guarantees, and expressly adds that those measures may be modified where circumstances change substantially. BOE-A-1889-4763
Art. 146 CC. The amount of maintenance is to be proportionate to the means of the person providing it and to the needs of the person receiving it. This is the substantive rule that allows maintenance to be reviewed both when the payer's income falls and when the child's needs change. BOE-A-1889-4763

Each article checked against the consolidated text published in the BOE (the Spanish official gazette).

Frequently asked questions

Can I pay less while I wait for the judge to decide?

Not on your own initiative. Until another decision modifies the measure, maintenance is owed in full and the difference builds up as an enforceable debt. What can be done is to seek, in the claim itself, the provisional modification of article 775.3, which follows article 773 and allows an immediate adjustment while the case is decided.

From when does the new maintenance apply if I win?

Article 775 sets no period for seeking modification, but the settled criterion of the courts is that the new amount applies from the filing of the claim and not from the day circumstances changed. That is why delay in filing costs money: earlier instalments remain owed at the old amount and are recovered by enforcement.

Is a small drop in salary enough to review maintenance?

Hardly. Article 775 requires that circumstances have changed substantially, and article 146 of the Código Civil measures the amount by the proportion between the payer's means and the recipient's needs. A minor or passing swing does not break that proportion. A dismissal with a recognised benefit, an incapacity or a lasting change of income does break it.

Can I ask to change both custody and maintenance at once?

Yes, and it usually makes sense. Article 775 refers to modifying the measures ordered, without limiting them, and a change of custody necessarily drags the financial calculation with it. Each request does need its own evidence: custody is decided on the children's interest and the real care calendar, and maintenance on proven income and needs.

What if my ex accepts the reduction in writing? Do I need the court?

A private agreement does not replace the judgment and does not prevent the difference being claimed later. Article 90.3 of the Código Civil does allow the measures to be modified by a new agreement approved by the judge, and those agreed before the court clerk or in a public deed by a new agreement with the same requirements. What is not approved cannot be enforced.

This guide explains how the action works in general. It does not replace the study of your own case: deadlines depend on when things happened and on what you have done since.