ForHosting KIT · Developer Utilities

Progressive income tax calculator

Progressive income tax means each slice of taxable income is charged at its own marginal rate, so the bill is not simply top-rate times total income.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

This progressive income tax calculator accepts any non-negative taxable income and an ordered list of brackets you supply—upper thresholds and rate percentages—then walks the schedule band by band to return tax owed, after-tax income, effective rate, and the marginal rate that applies to the last dollar. Model a simple three-band schedule for teaching, paste a national or state table for planning sketches, or run the same contract in product code without hard-coding one jurisdiction. The engine is pure deterministic arithmetic with no tax-year tables, no network lookup, and no randomness, so worksheets, demos, and CI fixtures always agree. Use it free in the browser or call the API at $0.002 per successful request when automation needs the identical result shape.

How to use it

Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.

Check your inputs

Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.

Use it again or automate it

Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.

What you can do with it

Get an answer now

Enter one set of values and see the result without building a spreadsheet or script.

Compare scenarios

Change one value at a time and rerun the calculation to understand what affects the result.

Automate repeated work

Use the API when the same calculation needs to run inside your product or workflow.

FAQ

How do I use this capability?

Complete the fields above and run it on this page. The form highlights anything that needs attention.

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/finance/income-tax-brackets

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/finance/income-tax-brackets \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"taxable_income":50000,"brackets":[{"upper":10000,"rate_percent":10},{"upper":40000,"rate_percent":12},{"upper":100000,"rate_percent":22}]}'

const res = await fetch("https://api.kit.forhosting.com/finance/income-tax-brackets", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "taxable_income": 50000,
    "brackets": [
      {
        "upper": 10000,
        "rate_percent": 10
      },
      {
        "upper": 40000,
        "rate_percent": 12
      },
      {
        "upper": 100000,
        "rate_percent": 22
      }
    ]
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/finance/income-tax-brackets",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "taxable_income": 50000,
    "brackets": [
        {
            "upper": 10000,
            "rate_percent": 10
        },
        {
            "upper": 40000,
            "rate_percent": 12
        },
        {
            "upper": 100000,
            "rate_percent": 22
        }
    ]
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/finance/income-tax-brackets", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"taxable_income":50000,"brackets":[{"upper":10000,"rate_percent":10},{"upper":40000,"rate_percent":12},{"upper":100000,"rate_percent":22}]}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"taxable_income":50000,"brackets":[{"upper":10000,"rate_percent":10},{"upper":40000,"rate_percent":12},{"upper":100000,"rate_percent":22}]}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/finance/income-tax-brackets", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "taxable_income": 50000,
  "brackets": [
    {
      "upper": 10000,
      "rate_percent": 10
    },
    {
      "upper": 40000,
      "rate_percent": 12
    },
    {
      "upper": 100000,
      "rate_percent": 22
    }
  ]
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "finance.income_tax_brackets",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Read the full KIT documentation →