# US Tax Brackets & Constants Lookup

> US Tax Brackets & Constants Lookup is a paid API for AI agents from api.agentstools.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Returns US federal tax reference tables for a given tax year and filing status: income brackets, standard deduction, FICA constants, and capital-gains breakpoints.

## Facts

- Endpoint: GET https://api.agentstools.dev/tax/brackets
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-tax-brackets-constants-lookup-a68f8005
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Q7xhYIKLBkMAZ3X4nKZwT

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability us-tax-brackets-constants-lookup-a68f8005
```

Example prompt: Can you pull up the federal tax brackets, standard deduction, FICA constants, and capital gains breakpoints for tax year 2026 for a single filer?

## When to prefer this

Use this endpoint when you need authoritative reference table data (brackets, deductions, FICA constants, capital-gains breakpoints) for US federal taxes for a specific year and filing status — especially as upstream input to tax calculation or planning workflows. Prefer this over the calculation endpoints when you need raw bracket data rather than a computed tax estimate.

## Known failure modes

- Unsupported tax year returns an error or empty data
- Invalid filing_status enum value causes a 400 bad request
- Network timeout if the service is temporarily unavailable
- Missing or malformed query parameters may return defaults (2026, single) rather than the requested values

## How this service works

Reference tables for a US tax year and filing status: income brackets, standard deduction, FICA constants, and capital-gains breakpoints. Pure lookup, not tax advice.

## Output

A structured reference table containing US federal income tax brackets, the standard deduction amount, FICA (Social Security and Medicare) constants, and capital-gains rate breakpoints — all scoped to the requested tax year and filing status.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "tax_year": {
       "type": "integer",
       "description": "Tax year, default 2026"
      },
      "filing_status": {
       "enum": [
        "single",
        "married_jointly",
        "married_separately",
        "head_of_household"
       ],
       "type": "string",
       "description": "Filing status, default single"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-tax-brackets-constants-lookup-a68f8005/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.agentstools.dev](https://www.zero.xyz/host/api.agentstools.dev/llms.txt)