# Roth Conversion Tax Cost Calculator

> Roth Conversion Tax Cost Calculator is a paid API for AI agents from x402toll.com, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-14).

Calculates the incremental federal income tax cost of converting a given amount to a Roth IRA in a single year, showing marginal rates before and after the conversion.

## Facts

- Endpoint: POST https://x402toll.com/v1/retirement/roth-conversion
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/roth-conversion-tax-cost-calculator-fca02c2a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8PPzU-iaf-x5nIPLT9eK5

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 roth-conversion-tax-cost-calculator-fca02c2a -d '<json body>'
```

Example prompt: I'm thinking of converting $60,000 from my traditional IRA to a Roth this year — I'm single and my other taxable income is about $85,000. How much extra federal tax will that Roth conversion cost me, and what marginal rates am I at before and after?

## When to prefer this

Use this endpoint when you need to compute the precise incremental federal income tax cost of a Roth IRA conversion for a single tax year, broken down by pre- and post-conversion marginal rates. Prefer this over generic tax calculators when the user's specific question is about the marginal tax impact of stacking a Roth conversion on top of existing taxable income, especially for planning 'what-if' scenarios.

## Known failure modes

- conversionAmount or otherTaxableIncome exceeds maximum allowed value (1,000,000,000) — returns validation error
- Invalid or missing filingStatus enum value — returns schema validation error
- Non-numeric values for conversionAmount or otherTaxableIncome — returns 400 bad request
- Payment not received or insufficient USDC balance — returns 402 Payment Required

## How this service works

Federal tax cost of a Roth conversion in one year: the extra income tax from stacking the converted amount on top of your other taxable income, with the marginal rate before and after.

## Output

Returns the incremental federal income tax cost of the Roth conversion, the marginal tax rate bracket the filer was in before the conversion, and the marginal tax rate bracket pushed into after stacking the conversion amount on top of other taxable income.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "filingStatus": {
   "enum": [
    "single",
    "mfj"
   ],
   "type": "string",
   "default": "single"
  },
  "conversionAmount": {
   "type": "number",
   "maximum": 1000000000,
   "minimum": 0
  },
  "otherTaxableIncome": {
   "type": "number",
   "default": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/roth-conversion-tax-cost-calculator-fca02c2a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402toll.com](https://www.zero.xyz/host/x402toll.com/llms.txt)