Overview
An income tax API for US federal and state tax calculation, built for apps that need to calculate taxes from a salary. Income Tax Calculator works by applying the official federal income tax brackets to your gross income after the standard deduction. It calculates the tax owed at each bracket level and returns a detailed breakdown including effective and marginal tax rates. Add fica=true to get take-home pay after the employee share of Social Security (capped at that year's wage base) and Medicare, including the 0.9% Additional Medicare Tax, with the FICA amounts themselves itemized on paid plans. Add state with a two-letter code (any of the 50 states or DC) to get state income tax alongside: the state's standard deduction and personal exemption are taken off the same income, its brackets applied, and any exemption credit subtracted, giving state tax, effective and marginal state rates, combined federal and state tax, and income after both. States with no wage income tax return zero. State figures come from the Tax Foundation's annual state table; phase-outs, recapture, local income taxes and credits beyond the exemption credit are not modelled, and the state's footnotes say where they apply.
Live Test Income Tax Grounding Data for AI Agents Source →
The tool
Once your client is connected to the VerveContext server, this appears in its tool list as IncomeTaxGroundingDataforAIAgents. It is read-only and open-world — it fetches and never mutates anything on your side — so most clients call it without asking you to confirm.
{
"name": "IncomeTaxGroundingDataforAIAgents",
"arguments": {
"income": "85000",
"rate": "22"
}
}You do not name the tool yourself; the model picks it. Asking about 85000 in the terms this source covers is enough for it to reach for IncomeTaxGroundingDataforAIAgents on its own — naming it explicitly also works, and is the way to force the call.
Connecting
One server URL covers every source in the catalog, including this one. Authorization is OAuth: the client opens a browser once, and there is no key to paste into a config file.
{
"mcpServers": {
"vervecontext": {
"url": "https://api.vervecontext.com/v1/mcp"
}
}
}https://api.vervecontext.com/v1/mcpPer-client setup — Claude, Cursor, VS Code, ChatGPT — is on the MCP setup page.
Arguments
These are the properties on the tool's inputSchema, so a well-behaved client validates them before the call is made. Premium arguments are accepted on every plan but only take effect on plans that include them.
| Argument | Type | Description |
|---|---|---|
incomeRequired | number | Gross annual income in USD range 0–∞ |
rateRequired | number | Tax rate as a percentage (e.g., 22 for 22%) range 0–100 |
deductionOptional | number | Optional deduction amount to subtract from income before calculating tax range 0–∞ |
What the model gets back
The result carries a structuredContent object matching the tool's declared outputSchema, so a client reads fields without parsing prose. status is "ok" and error is null on success; a null field means the value was not available for that input, not that the call failed.
{
"status": "ok",
"error": null,
"data": {
"year": 2025,
"filing_status": "single",
"income": 85000,
"standardDeduction": 15000,
"taxableIncome": 70000,
"totalTax": 10313.88,
"effectiveRate": "12.13%",
"marginalRate": "22%",
"incomeAfterTax": 74686.12,
"monthlyTax": 859.49,
"monthlyIncome": 6223.84,
"brackets": [
{
"rate": 0.1,
"ratePercent": "10.0%",
"rangeMin": 0,
"rangeMax": 11925,
"taxableAmount": 11926,
"taxAmount": 1192.6
},
{
"rate": 0.12,
"ratePercent": "12.0%",
"rangeMin": 11926,
"rangeMax": 48475,
"taxableAmount": 36550,
"taxAmount": 4386
},
{
"rate": 0.22,
"ratePercent": "22.0%",
"rangeMin": 48476,
"rangeMax": 103350,
"taxableAmount": 21524,
"taxAmount": 4735.28
}
],
"fica": {
"total": 6502.5,
"socialSecurityRate": 0.062,
"socialSecurityWageBase": 176100,
"socialSecurityTax": 5270,
"medicareRate": 0.0145,
"medicareTax": 1232.5,
"additionalMedicareThreshold": 200000,
"additionalMedicareTax": 0
},
"takeHomePay": 68183.62,
"monthlyTakeHomePay": 5681.97,
"totalEffectiveRate": "19.78%"
}
}
Response fields
Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.
| Field | Type | Example | Description |
|---|---|---|---|
year | number | 2025 | Tax year used for calculation |
filing_status | string | single | Filing status used |
income | number | 85000 | Original gross income provided |
standardDeduction | number | 15000 | Standard deduction applied based on filing status |
taxableIncome | number | 70000 | Income after standard deduction |
totalTax | number | 10313.88 | Total federal tax owed |
effectiveRate | string | 12.13% | Effective tax rate as percentage |
marginalRate | string | 22% | Marginal tax rate (highest bracket) |
incomeAfterTax | number | 74686.12 | Take-home income after tax |
monthlyTax | number | 859.49 | Monthly tax amount (totalTax / 12) |
monthlyIncome | number | 6223.84 | Monthly take-home income (incomeAfterTax / 12) |
bracketsPremium | array[3] | Detailed breakdown of tax by bracket | |
brackets.0.ratePremium | number | 0.1 | Marginal rate for the band, as a fraction |
brackets.0.ratePercentPremium | string | 10.0% | Marginal rate for the band, formatted as a percentage |
brackets.0.rangeMinPremium | number | 0 | Income at which the band starts |
brackets.0.rangeMaxPremium | number | 11925 | Income at which the band ends |
brackets.0.taxableAmountPremium | number | 11926 | How much of the income falls inside this band |
brackets.0.taxAmountPremium | number | 1192.6 | Tax owed on the portion falling in this band |
ficaPremium | object | {…} | Employee FICA on the income as wages; present only with fica=true, null when the wage base for the year is not known |
fica.totalPremium | number | 6502.5 | Total employee FICA: Social Security plus Medicare plus Additional Medicare Tax |
fica.socialSecurityRatePremium | number | 0.062 | Employee Social Security rate, as a fraction (0.042 in 2011-2012) |
fica.socialSecurityWageBasePremium | number | 176100 | Wages above this amount owe no Social Security tax for the year |
fica.socialSecurityTaxPremium | number | 5270 | Employee Social Security tax on wages up to the wage base |
fica.medicareRatePremium | number | 0.0145 | Employee Medicare rate, as a fraction |
fica.medicareTaxPremium | number | 1232.5 | Employee Medicare tax on all wages |
fica.additionalMedicareThresholdPremium | number | 200000 | Wages above which the 0.9% Additional Medicare Tax applies for the filing status; null before 2013 |
fica.additionalMedicareTaxPremium | number | 0 | 0.9% Additional Medicare Tax on wages above the threshold |
takeHomePay | number | 68183.62 | Income after federal income tax and FICA; present only with fica=true |
monthlyTakeHomePayPremium | number | 5681.97 | Monthly take-home pay (takeHomePay / 12); present only with fica=true |
totalEffectiveRatePremium | string | 19.78% | Federal income tax plus FICA as a percentage of income; present only with fica=true |
Why ground on it
A model can produce something that looks like this answer from its training data, and be confidently out of date or simply wrong. This source returns the current value in a shape you can check, which is the difference between an answer you can cite and one you have to hedge.
Point an evaluation at year: it is the field most worth pinning a claim to, and it is either present and current or absent — never plausibly invented.
Failure modes
Errors come back as tool errors carrying a sentence the model can act on, not a bare status code. Error handling covers the full list.
| Status | What it means |
|---|---|
400 / 422 | The arguments did not validate. The message names the offending one. |
401 | The OAuth session is invalid or expired — reconnect the server. |
403 | Blocked by a key restriction or an IP allow-list. Never a bad identity. |
404 | This source is not part of VerveContext. Check the catalog. |
429 | Out of credits, or a brief rate limit. The message tells them apart. |
A call costs 2 credits each time the tool actually runs; a model that reasons about the tool without calling it costs nothing.
Use cases
- Job Offer Evaluation
- When weighing multiple job offers, candidate compensation portals calculate net take-home pay and federal tax obligations across different filing statuses.
- Payroll Withholding Estimation
- HR platforms estimate employee annual federal tax liability and monthly deductions directly from gross salary inputs to forecast withholdings.
- Retirement Distribution Modeling
- To model retirement drawdowns, financial advisors project changes in effective and marginal rates as client taxable distributions shift across tax bands.
- Custom Rate Invoicing
- Compute estimated tax obligations and remaining net earnings for freelance contracts using custom tax percentages and project deductions.
Other ways to use Income Tax Grounding Data for AI Agents
Set up Income Tax Grounding Data for AI Agents on VerveContext, or reach the same source a different way. Your VerveContext account and credits work on all of them — one key, one balance.
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