Common Alimony Child Support mistakes in Brazil
6 min read
Published April 15, 2026 • By DocketMath Team
The top mistakes
Run this scenario in DocketMath using the Alimony Child Support calculator.
Below are common alimony and child support mistakes we see in Brazil when people use DocketMath (calculator: alimony-child-support) and when they prepare documents to match what Brazilian courts typically look for. This is not legal advice—think of it as a practical checklist to reduce avoidable errors and input/output mismatches.
1) Mixing up child support vs alimony categories
A frequent error is treating these obligations as interchangeable when entering facts or drafting requests.
- Child support (alimentos ao menor): generally tied to the child’s needs and the parents’ paying capacity.
- Spousal/partner support (alimentos entre cônjuges/companheiros): generally tied to the adult-to-adult legal basis for support after separation.
Why it matters in Brazil: courts typically evaluate different factual elements depending on the category. If you feed DocketMath inputs meant for child support into an alimony scenario (or vice versa), the output may not reflect the case theory you’re presenting.
2) Using outdated income information (and inconsistent time windows)
Another common error is calculating support based on old or incomplete income.
Typical examples:
- using last year’s salary even if your pay changed in 2024/2025
- including only base salary while omitting recurring variable components (commissions, overtime, bonuses)
- estimating self-employed income without consistent documentation
DocketMath outputs can shift materially when income inputs change. Even a “small” correction—like adding a regular average commission—can change the monthly number enough to create tension between your filings and your calculator run.
Note: Brazilian support determinations often depend on the payer’s financial capacity and the beneficiary’s needs. Incomplete or stale income data is one of the fastest ways to end up requesting an amount that doesn’t match what’s supportable.
3) Entering dependents incorrectly (including people who are not eligible dependents)
People sometimes include:
- other relatives supported informally
- children from new relationships without clear documentation
- stepchildren without the factual/legal basis needed
In Brazil, the “who counts” issue can be case-specific. If the dependent set is wrong, DocketMath can overstate or understate the support burden compared with what the court expects to analyze.
4) Not aligning “fixed” vs percentage/flexible requests with how income changes
Many filings ask for a single lump figure without clarifying the relationship to future income changes.
Even when DocketMath provides a monthly estimate, courts and parties often have to work with the reality that income can fluctuate—especially when earnings include variable components. A common problem is treating the numeric output as the only “story,” instead of explaining the basis behind it and how it relates to the payer’s earnings and custody/expense facts.
5) Ignoring actual living arrangements and custody impact
Child support is not calculated in a vacuum—how the family actually functions matters.
Common document mistakes:
- describing a residence/custody situation that doesn’t match the evidence
- missing details about who covers school, medical, or childcare expenses
- failing to document whether one parent directly pays recurring costs
If your real-world expenses and arrangements differ from your inputs, you may get a number that looks reasonable mathematically—but still mismatched to the facts the court evaluates.
6) Treating initial figures as unchangeable
Brazilian law allows revisiting support when circumstances change. Even if the process is not immediate, you should expect that:
- initial amounts are usually not “forever”
- changes in income, employment status, or the child’s needs often trigger recalculation discussions
So a error is freezing thinking at month one and assuming the first computed number will remain accurate without updates.
7) Using DocketMath inconsistently across drafts
We often see the same case handled with different numbers in different places, such as:
- negotiation messages
- the initial petition draft
- spreadsheets or working documents
- later follow-up updates
Inconsistency undermines credibility and can create delays. DocketMath is most helpful when you use one set of inputs as the “source of truth,” then update all drafts using the same numbers.
8) Skipping the “documentation-ready” detail
Even if DocketMath estimates a monthly number, Brazilian court evaluation often expects supporting detail, such as:
- proof of income (depending on the scenario: pay slips, tax filings, bank records)
- evidence of recurring expenses and the child’s needs
- records tied to custody/parenting arrangements
A common error is presenting a number without planning the evidence that supports the assumptions behind it.
How to avoid them
Use the checklist below to reduce errors. The goal isn’t to “game” outcomes—it’s to align inputs, story, and outputs.
Use a written checklist for inputs, document each source, and run a quick sensitivity check before finalizing the result. When two runs differ, compare inputs line by line and re-run with one variable changed at a time.
Step 1: Separate child support and alimony in your workflow
Before using DocketMath:
Practical payoff: fewer mismatches between what you request and what DocketMath is modeling.
Step 2: Use a consistent income time window (and document it)
When entering income in DocketMath:
Then align documentation to the same window:
Step 3: Validate the dependent list
Before finalizing inputs:
If you’re unsure, run DocketMath twice—once with the contested dependent included and once excluded—to see how sensitive the output is. Large sensitivity is a sign you should tighten the factual basis.
Step 4: Mirror actual custody and expense responsibility
Update your facts to match reality:
Treat DocketMath as a calculator, not a fact-finder: the output will only be as credible as your scenario inputs.
Step 5: Keep one “single calculation master”
Operationally:
Link your filings to the same numeric story. If you revise, revise everything consistently.
Step 6: Plan for future changes
Support can be revisited when circumstances materially change. To reduce friction later, plan for updates such as:
With DocketMath, re-run when income or need facts change and keep a dated calculation log.
Step 7: Pressure-test the numbers with scenario comparisons
Try scenario comparisons to understand what moves the result:
This doesn’t replace evidence—it helps you identify which assumptions drive the biggest swings, so you can focus documentation where it matters most.
Step 8: Turn outputs into a documentation plan
After you get a monthly figure from DocketMath, build a simple evidence map:
| Calculator input assumption | Output effect | Evidence you’ll want |
|---|---|---|
| Monthly gross income average | High impact | Pay slips / tax documentation / bank corroboration |
| Dependent count | Medium impact | Birth records / custody facts / dependency basis |
| Shared expenses assumptions | Medium–high impact | School/medical receipts, recurring payment records |
| Custody arrangement parameters | Medium impact | Parenting schedule + proof of costs |