iTax

iTax is a free/open source multi-platform implementation and extension of the Australian Tax Offices(ATO) 'e-tax' software. phase 1 of this to create a free/open source multi-platform implementation of the ATOs e-tax phase 2 is to extend e-tax.

MoneyJar

MoneyJar is a Java library to help with implementations for demanding financial applications. This library simplifies money management, rounding, currency conversion, tax calculation (tax-on-tax, multiple tax) and invoice management. Highly configurable.

PalmOS Philippine Income Tax Calculator

A PalmOS application that calculates the monthly and yearly income tax incurred by employees according to the Philippine Income Tax Laws.

UK Tax and Finance

UK Tax and Finance is a small suite of open source applications for finance and (uk) tax related calculations. Two versions exist: gnome-python and javascript.

Open Tax Solver

OTS is an easy-to-use text-based C-program for calculating Tax Form entries and tax-owed or refund-due, for Federal or State personal income taxes. Includes versions for US 1040, Scheds A, B, C, D, and forms for several states, as well as Canada and UK.

PHPBalanceSheet

PHPBalanceSheet is, as its name suggests, a balance sheet application implemented in PHP. The idea came from a real-world situation: filing tax returns, which requires the collating of taxable income and tax-deductable expenses.

Open Tax Return

This project is designed to help tax payer calculate their tax return for free.

TaxACT

Install tax software directly to your computer and prepare, print, and e-file your taxes with ease.