income-tax-sg

Calculate individual income tax for Singapore tax residents.

Installation

npm install income-tax-sg

Usage

Calculate tax from chargeable income

import { calculateTaxFromChargeableIncome } from "income-tax-sg";

const tax = calculateTaxFromChargeableIncome(120_000);
// 7950

Calculate tax from income breakdown

import { calculateTax } from "income-tax-sg";

const result = calculateTax({
  employmentIncome: 150_000,
  employmentExpenses: 2_000,
  otherIncome: 5_000,
  donations: 1_000,
  personalReliefs: 20_000,
  taxRebates: 200,
});
// {
//   chargeableIncome: 130500,
//   grossTax: 9525,
//   netTaxPayable: 9325
// }

All fields in the params object are optional and default to 0. Several fields are grouping categories — you should sum the relevant items before passing them in:

• otherIncome — the total of all non-employment income, including:

  • Trade, business, profession or vocation income
  • Dividends
  • Interest
  • Rent from property
  • Royalty, charge, estate/trust income
  • Gains or profits of an income nature

• donations — approved donations (before the 2.5× tax deduction multiplier, which is applied automatically)

• personalReliefs — the total of all personal reliefs claimed, including:

  • Earned income relief
  • Spouse relief / spouse relief (disability)
  • Qualifying child relief (QCR) / child relief (disability)
  • Working mother's child relief
  • Parent relief / parent relief (disability)
  • Grandparent caregiver relief
  • Sibling relief (disability)
  • CPF/provident fund relief
  • Life insurance relief
  • CPF cash top-up relief (self, dependant and Medisave account)
  • Supplementary Retirement Scheme (SRS) relief
  • NSman (self/wife/parent) relief

  Note: the $80,000 overall relief cap is applied automatically.

• taxRebates — the total of all tax rebates, including:

  • Parenthood tax rebate
  • Any other applicable tax rebates

Assessment year

Both functions accept an optional assessment year parameter (default: 2026). Must be an integer >= 2026.

calculateTaxFromChargeableIncome(120_000, 2026);
calculateTax({ employmentIncome: 120_000 }, 2026);

Calculation logic

1. Net employment income = employment income − employment expenses (floored at 0)
2. Total income = net employment income + other income
3. Assessable income = total income − (donations × 2.5)
4. Chargeable income = assessable income − personal reliefs (capped at $80,000)
5. Gross tax = progressive tax on chargeable income
6. Net tax payable = gross tax − tax rebates (floored at 0)

Sources

• IRAS — Individual Income Tax Rates
• IRAS — Income Tax Calculator for Tax Resident Individuals (YA2026)

License

ISC