Progressive tax demos help teams prototype payroll sheets — production must use official engines or provider APIs.
payrollTaxCalculation filters TaxBrackets by filing status and applies marginal rates between min and max.
taxOut is a simplified estimate: no credits, pre-tax deductions, or local levies.
Replace brackets with your jurisdiction’s current table and have payroll review before any real use.
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Sheet / project setup
| Sheet | Column | Purpose |
|---|---|---|
| TaxBrackets | A filing | e.g. single |
| TaxBrackets | B min | Taxable income floor |
| TaxBrackets | C max | Ceiling (blank=open) |
| TaxBrackets | D rate | Marginal rate |
| Employees | B gross | Wage basis |
| Employees | C filing | Status key |
| Employees | D taxOut | Estimate |
What this script does
Marginal bracket tax estimate per employee.
Prerequisites
Bracket table for each filing status; gross defined (YTD vs period).
- Illustrative only
- Filing keys match
- Gross basis documented
Walkthrough
Build two brackets for single; compute a sample gross by hand and compare.
Edge cases
Using period gross with annual brackets is wrong — annualize or use period tables.
- Infinity top bracket
- No standard deduction in sample
Compliance disclaimer
This tutorial is for learning Apps Script patterns. Do not use it as a tax engine for real payroll without qualified review.
How to test
Employee just into second bracket pays first full band + partial second.
Hardening for production
Add pre-tax benefits subtraction before tax.
Variations
Call a payroll provider API instead of local brackets.
Full code: payrollTaxCalculation()
Load illustrative brackets, then run payrollTaxCalculation() on sample employees only.
/**
* Illustrative payroll tax estimate from gross wages and bracket table.
* Not legal advice — replace brackets with your jurisdiction rules.
*/
const EMP = "Employees"; // A id, B gross, C filing, D taxOut
const BR = "TaxBrackets"; // A filing, B min, C max, D rate
function payrollTaxCalculation() {
const ss = SpreadsheetApp.getActive();
const brackets = ss.getSheetByName(BR).getDataRange().getValues().slice(1).map(function (r) {
return {
filing: String(r[0]),
min: Number(r[1]) || 0,
max: r[2] === "" || r[2] == null ? Infinity : Number(r[2]),
rate: Number(r[3]) || 0,
};
});
const sheet = ss.getSheetByName(EMP);
const values = sheet.getDataRange().getValues();
for (let i = 1; i < values.length; i++) {
const gross = Number(values[i][1]) || 0;
const filing = String(values[i][2]);
let tax = 0;
brackets.filter(function (b) { return b.filing === filing; }).forEach(function (b) {
if (gross <= b.min) return;
const taxable = Math.min(gross, b.max) - b.min;
if (taxable > 0) tax += taxable * b.rate;
});
values[i][3] = Math.round(tax * 100) / 100;
}
sheet.getRange(1, 1, values.length, values[0].length).setValues(values);
}- Line 6: Marginal rate table by filing status.
- Line 25: Filters brackets to the employee status.
- Line 27: Taxable slice in the band.
- Line 28: Marginal tax for the slice.
- Line 5: Estimated tax column.
Deploy this example
- 01
Open Apps Script
In the bound spreadsheet: Extensions → Apps Script. For standalone projects, create one at script.google.com and link your Sheet by ID.
- 02
Paste and save
Add a .gs file, paste the code below, rename constants at the top (sheet names, column letters, API property keys), then save.
- 03
Authorize once
Run the main function from the editor. Accept OAuth scopes when prompted — triggers cannot run until authorization succeeds once.
- 04
Add the trigger
Triggers → Add trigger → choose the handler function and event (time-driven, on edit, or on form submit). Delete test triggers before production.
Before you run: payroll tax demo
- 1Understood as illustrative only
- 2Bracket mins/maxes contiguous
- 3Filing statuses aligned
- 4Gross basis (annual vs period) correct
- 5No production paychecks from this output
- 6Payroll specialist review if adapting
Frequently asked questions
No — real FIT uses IRS publications, withholding tables, W-4, etc.
Add separate flat-rate calculations with wage bases.
Subtract from gross before bracket math.
Run state/local tables similarly and sum.
Open top bracket when max cell blank.
Not without replacing logic with a certified payroll engine/API.
Compute tax on YTD taxable wages minus tax already withheld.