Freelance Quarterly Tax Estimate Calculator

WHAT IT DOES

This userscript helps freelancers and self-employed workers estimate and plan for quarterly tax payments. It scans any webpage for text-based income figures, invoices, or payment records, or allows manual entry, to calculate quarterly estimated tax payments. It extracts income from the page, applies tax rate estimates, calculates the quarterly tax liability, and shows the payment amounts for each quarter (Q1-Q4). The script tracks income by quarter, suggests withholding adjustments, and exports the quarterly tax estimate as CSV or HTML. It accounts for deductions and self-employment tax, and provides a year-to-date tax summary.

WHERE IT RUNS

The script works on any webpage with income figures—freelance platforms, invoicing pages, payment portals, or any page with dollar amounts. It runs entirely within your browser, reading only the visible content of the current page. It does not track your browsing history, access other tabs, or send any data externally. All income data is processed and stored locally.

HOW TO USE

After installation, open the panel by clicking the tool's icon in the BotGentz sidebar. Enter your income for each quarter (Q1-Q4) in the input fields. Set your income tax rate and filing status. Click "Calculate Quarterly Taxes" to see a quarterly breakdown of income, self-employment tax, income tax, and total tax per quarter. The summary shows total income, total tax, and effective rate. Payment due dates are displayed. Click "Extract from page" to scan the current page for income figures and auto-distribute across quarters. Use the export dropdown to choose CSV or HTML. Click "Export" to download.

THE TECHNICAL MECHANISM

This script calculates self-employment tax at 15.3% of taxable income for each quarter. Income tax is calculated as quarterly taxable income multiplied by the user-provided tax rate. Taxable income is quarterly income minus deductions (currently set to 0, but user-configurable). The script displays a table with quarterly income, self-employment tax, income tax, and total tax. It calculates year-to-date totals and effective tax rate. The extraction function scans for dollar amounts and distributes them evenly across quarters for quick estimation. All data is persisted using GM_setValue.

THE PANEL

The panel is draggable anywhere on the screen and remembers its position between sessions. It can be collapsed to a small floating bubble to minimize distraction, and expanded again with a single click. The panel's width can be adjusted, and pressing the Escape key closes it instantly. All settings and income data are persisted locally using GM_setValue, so your calculations remain intact across page reloads and browser restarts.

PLEASE NOTE

This userscript requires the free BotGentz extension to function. The script extracts figures from page text—it may not capture all numbers correctly. Review and adjust extracted data as needed. The tax calculations are estimates and do not constitute tax advice. Consult a tax professional for accurate filing. The script does not access external APIs or store any data outside your browser. No data from your browsing is stored or transmitted anywhere—all processing occurs entirely in your browser.