# PrepReturns

> Professional tax preparation built inside a tax practice. From source evidence to a finished S-corporation return package. Form 1040 comes next.

A practitioner-led project from Trio Tax. Deterministic calculations, source provenance, explicit unknowns, professional review, and AI-assisted development. Private today; likely to become open source. Alpha 14 — human testing and broader operating-business coverage.

## Public content

- [Tax preparation. From the source.](https://prepreturns.com/): Professional tax preparation built inside a tax practice. From source evidence to a finished S-corporation return package. Form 1040 comes next.
- [S-Corp Engine](https://prepreturns.com/s-corp/): Follow conventional S-corporation preparation from reviewed sources through Guided Preparation, deterministic calculations and official IRS-form output.
- [S-Corp capabilities](https://prepreturns.com/s-corp/capabilities/): Explore the supported S-corporation return universe: owners, basis, operations, assets, corporate reporting, review and output.
- [S-Corp limitations](https://prepreturns.com/s-corp/limitations/): The boundaries of the PrepReturns S-Corp Engine, including specialized transactions, owner-level limitations and filing services.
- [How it works](https://prepreturns.com/how-it-works/): Six stages connect source documents, reviewed facts, professional decisions, reproducible calculations and a saved return package.
- [Source evidence](https://prepreturns.com/evidence/): How PrepReturns distinguishes original evidence, proposed facts, professional corrections and the established facts behind the return.
- [Technology](https://prepreturns.com/technology/): The architecture behind PrepReturns: deterministic tax logic, explicit unknowns, provenance, immutable preparation history and official forms.
- [How PrepReturns was built](https://prepreturns.com/development/): The Alpha story of practitioner-led, AI-assisted tax software development, from deterministic core to human testing and broader business coverage.
- [Form 1040 comes next](https://prepreturns.com/1040/): A separate individual-return architecture carrying forward evidence, deterministic calculations and professional review from the S-Corp Engine.
- [Where PrepReturns goes next](https://prepreturns.com/roadmap/): A durable direction for PrepReturns: S-corporation human testing now, individual returns next, and an open-source future.
- [The principles behind PrepReturns](https://prepreturns.com/principles/): Ten practical commitments to evidence, traceability, deterministic calculations, professional control and software practitioners can shape.
- [PrepReturns Project Brief](https://prepreturns.com/project-brief/): A precise summary of the project, S-Corp Engine, preparation architecture, development process, current scope and future direction.
- [The PrepReturns Journal](https://prepreturns.com/journal/): Essays from the practice on professional tax software, evidence, engineering, interoperability and the possibility of building something different.
- [Built from a tax practice.](https://prepreturns.com/about/): The practitioner perspective behind PrepReturns and its relationship to Trio Tax and Trio Ledger.
- [Let's compare notes.](https://prepreturns.com/collaborate/): Conversations with tax professionals, engineers, researchers, and tax-software companies about PrepReturns and the future of professional preparation.
- [Interested in the project?](https://prepreturns.com/contact/): Contact PrepReturns through Trio Tax to discuss professional workflow, architecture, testing, integrations, or collaboration.
- [Tax software you can actually change.](https://prepreturns.com/open-source/): PrepReturns is private today and being built with open source in mind: inspection, modification, integration, and disciplined contribution.
- [Privacy, in plain language.](https://prepreturns.com/privacy/): How the PrepReturns public information website uses Google Tag Manager and Google Analytics 4 and handles hosting logs and external contact links.
- [Security and the public site](https://prepreturns.com/security/): The security boundaries of the PrepReturns website: static project information, synthetic examples, no taxpayer uploads, and an existing contact path.
- [We needed better tax software. So we started building it.](https://prepreturns.com/story/): How preparation problems inside Trio Tax became an end-to-end S-corporation software project, with Form 1040 next.
- [The Straightforward 90%](https://prepreturns.com/straightforward-90/): PrepReturns' scope framework: conventional professional returns, explicit boundaries, and deliberate expansion.
- [Terms for this public website.](https://prepreturns.com/terms/): The scope and terms of PrepReturns.com: public project information and synthetic software examples, not tax advice or a filing service.
- [Why another tax program?](https://prepreturns.com/why/): The preparation problems behind PrepReturns: repeated entry, fragmented evidence, limited interoperability, and too little control over professional tools.
- [Why I'm Building Another Tax Program](https://prepreturns.com/journal/why-im-building-another-tax-program/): The practitioner frustrations and product questions behind PrepReturns, a preparation system built inside Trio Tax.
- [The Straightforward 90%](https://prepreturns.com/journal/the-straightforward-90/): Why conventional returns deserve a deliberate product model, and why straightforward does not mean small or effortless.
- [Source Documents Should Be Evidence, Not Data-Entry Instructions](https://prepreturns.com/journal/source-documents-are-evidence/): A better preparation workflow separates what a document says, what software reads, and what the professional establishes.
- [Why Tax Calculations Should Be Deterministic](https://prepreturns.com/journal/why-tax-calculations-should-be-deterministic/): AI can help build tax software. Explicit facts, rules, and reproducible calculations should produce the return.
- [Every Number Needs a Story](https://prepreturns.com/journal/every-number-needs-a-story/): A return should explain where an amount came from, which decisions shaped it, and which preparation it belongs to.
- [Let Me Test-Drive Your Tax Software](https://prepreturns.com/journal/let-me-test-drive-your-tax-software/): A better way to evaluate professional software: prepare, correct, inspect, and ask technical questions in a synthetic case.
- [The Problem With Feature Requests](https://prepreturns.com/journal/the-problem-with-feature-requests/): Practitioners know where the work breaks down. Better software needs a better relationship with that knowledge.
- [Tax Software Needs Real APIs](https://prepreturns.com/journal/tax-software-needs-real-apis/): Interoperability should preserve tax meaning, source history, and professional review—not simply move values between screens.
- [Can Professional Tax Software Be Open Source?](https://prepreturns.com/journal/open-source-professional-tax-software/): What inspectable, modifiable tax software could change for practitioners—and the review and maintenance it would still require.
- [What Can a Small Tax Firm Build Now?](https://prepreturns.com/journal/what-can-a-small-tax-firm-build-now/): PrepReturns explores how frontier AI changes the feasibility of building professional software while leaving the hard work intact.

## Additional formats

- [Public summaries and essays](https://prepreturns.com/llms-full.txt)
- [Journal RSS](https://prepreturns.com/rss.xml)