---
title: "Dependent-care FSA vs §21 credit comparator"
method: POST
path: "/v1/benefits/dependent-care"
tags: ["Tax"]
---

# Dependent-care FSA vs §21 credit comparator

`POST /v1/benefits/dependent-care`

## Request

- Base URL: `https://api.numeratica.com`
- URL: `https://api.numeratica.com/v1/benefits/dependent-care`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-API-Key`

Compares the two ways to get a tax benefit on child- and dependent-care costs: a dependent-care FSA (§129 — pre-tax, saving income + FICA at the marginal rate) vs the §21 child- and dependent-care tax credit (a percentage of eligible expenses). The §21 credit is computed by the tax engine, so its applicable-percentage schedule (incl. the 2026 OBBBA changes), the $3k/$6k expense cap by qualifying count, the AGI phase-down, and the nonrefundable limit all apply. Returns both benefits and the recommendation. Deterministic; not tax advice.

## Request body

- DependentCareRequest
  - `tax_year` 2025 | 2026, required
  - `filing_status` 'single' | 'mfj' | 'mfs' | 'hoh', required
  - `ordinary_income` number, required: Drives the §21 applicable percentage (by AGI) + credit headroom.
  - `dependent_care_expenses` number, required: Total eligible care costs for the year.
  - `qualifying_count` integer, required: 1 caps §21 at $3k; 2+ at $6k.
  - `marginal_tax_rate` number, required: For the FSA saving (income + FICA).
  - `fsa_contribution_limit` number: Overrides the year's §129 cap (2025: $5,000 / $2,500 MFS; 2026: $7,500 / $3,750, per OBBBA §70404). Set it to model an employer plan that hasn't adopted the increase.

## Response `200`

The FSA-vs-credit comparison

- DependentCareResponse
  - `result_id` string
  - `engine_version` string
  - `inputs` DependentCareRequest
    - `tax_year` 2025 | 2026, required
    - `filing_status` 'single' | 'mfj' | 'mfs' | 'hoh', required
    - `ordinary_income` number, required: Drives the §21 applicable percentage (by AGI) + credit headroom.
    - `dependent_care_expenses` number, required: Total eligible care costs for the year.
    - `qualifying_count` integer, required: 1 caps §21 at $3k; 2+ at $6k.
    - `marginal_tax_rate` number, required: For the FSA saving (income + FICA).
    - `fsa_contribution_limit` number: Overrides the year's §129 cap (2025: $5,000 / $2,500 MFS; 2026: $7,500 / $3,750, per OBBBA §70404). Set it to model an employer plan that hasn't adopted the increase.
  - `result` object
    - `fsa_contribution` number: min(expenses, the §129 limit).
    - `fsa_benefit` number: contribution × marginal rate.
    - `section_21_credit` number: The §21 credit on the expenses (nonrefundable).
    - `recommended` 'fsa' | 'credit' | 'either'
    - `better_by` number: The benefit gap between the two.
  - `disclaimer` string

## Other responses

- `400`: Invalid request
- `401`: Missing or invalid API key.
- `405`: Method not allowed
- `429`: The key's per-minute request budget is exceeded. Retry after the delay in the Retry-After header.
- `503`: A dependency (e.g. the key store) is temporarily unavailable, or the request exceeded its compute deadline. Retryable.

---

[API](https://skmtc.dev/numeratica/apis/numeratica-financial-planning-calculations-api.md) · [All operations](https://skmtc.dev/numeratica/apis/numeratica-financial-planning-calculations-api/llms.txt) · [OpenAPI document](https://skmtc.dev/numeratica/apis/numeratica-financial-planning-calculations-api/revisions/075bcfbd1ebf?raw)