Filed and Crimson Tree Software have launched the Open Tax Technology Alliance, releasing OpenTax, a free open-source federal 1040 calculation engine, and Open Tax Document, an open standard for Schedule K-1 and K-3 data exchange. OpenTax runs on macOS, Linux, and Windows without cloud dependency. It covers Form 1040 for tax year 2025 across 186 registered nodes and 131 input types, including W-2s, 1099s, and K-1s. The engine checks returns against IRS business rules and exports Modernized e-File XML. Open Tax Document provides a free standard for exchanging structured partnership tax data, published at github.com/opentaxdocument/otd-spec. It includes K-1 taxonomy, transmission formats, and AI-compatible tools. The Alliance aims to make tax calculation infrastructure freely available, arguing that core arithmetic is a solved problem. Both initiatives will remain free and unmonetised. The engine is licensed under AGPL v3, with a commercial option available.

Open Tax Technology Alliance launches with free 1040 engine. Published September 22, 2026, 9:00 a.m. EDT Tax solution specialists Filed and Crimson Tree Software have teamed up to launch the Open Tax Technology Alliance, a new organization dedicated to promoting and supporting open source software in the accounting technology space. As one of the Alliance's first initiatives, it has released a free 1040 tax calculation engine anyone can use, as well as an open data standard for partnership returns that bypasses PDFs in favor of digitized information. This Q&A offers insights from a conversation with David Yue, co-founder and CEO at Accordance, on the opportunity AI presents to accountants and why... Technology Editor Chris Gaetano is the technology editor for Accounting Today. He brings with him more than a decade of experience covering the accounting profession... Read full bio