What is PrepReturns?
PrepReturns is a practitioner-led professional tax-preparation project. Its current working engine focuses on conventional federal S-corporation returns: source documents and financial information, reviewed facts, preparation decisions, deterministic calculations, workpapers, diagnostics, official IRS forms and a saved return package.
This website is the public project showcase. It contains finished editorial explanations and synthetic product examples. It is separate from the private tax engine and does not offer a hosted preparation session, taxpayer upload, download, login or filing service.
Explore the S-Corp Engine or follow the preparation workflow.
Who built it, and why?
PrepReturns grew out of Trio Tax, a working tax practice. The central story is straightforward: we did not start a software company and go looking for a tax problem. We run a tax firm and started building the software we wanted to use.
The motivation includes repetitive transcription, fragmented review, software bugs and quality-control friction, difficult support paths, controlled sales demonstrations, unanswered technical questions, feature-request backlogs and limited or expensive integration access. These are product problems worth exploring, while recognizing the substantial breadth established professional software supports.
Trio Ledger is a related small-business ledger product. Trio Tax is the practice, Trio Ledger is the sibling bookkeeping product, and PrepReturns is the preparation project. Their relationship does not imply an implemented integration.
Read the project story and the reasons for building another tax program.
What does the S-Corp Engine do?
The engine connects supported sources and manual facts with Guided Preparation, direct workpapers and actual forms. The preparer reviews proposed information, resolves missing facts and makes the professional decisions. Calculations and saved output use the resulting established facts.
- Entity and owners
- Conventional federal S-corporation preparation with multiple individual shareholders and owner-specific reporting.
- Income and deductions
- Ordinary business income, deductions, book-to-tax adjustments, paid shareholder-loan interest and accountable-plan reimbursements.
- Stock basis and shareholder debt
- Owner-specific stock basis, bona fide direct debt, suspended loss character, restoration and supported Form 7203 output.
- Assets, vehicles and amortization
- Depreciation, supported section 179 and bonus/MACRS, dispositions, listed property, and startup, organizational and intangible amortization.
- Rental real estate
- Ordinary corporation-owned residential and commercial rentals with separate property reporting and Form 8825.
- Inventory and cost of goods sold
- Reviewed inventory rollforward and cost components, Form 1125-A, and distinct cost-of-goods-sold reporting.
- Corporate capital transactions
- Ordinary corporate stock, fund and other supported capital-asset sales with known basis, Schedule D (1120-S) and Form 8949.
- Payroll, officers and retirement
- Payroll reconciliation, officer compensation, applicable Form 1125-E, and bounded SEP and Solo 401(k) workflows.
- Official forms and corporate reporting
- Actual Form 1120-S, K-1, applicable supporting forms, book-to-tax schedules and corporate QBI information.
- Review, history and output
- Source review, Guided Preparation, workpapers, How calculated, optional diagnostics and saved professional return packages.
These are capability families, not a claim of unrestricted support for every transaction or form. The capability reference describes the supported patterns and their boundaries.
What return universe is it designed for?
The focus is the conventional operating business. A return can involve multiple owners, payroll, fixed assets, contributions and distributions, shareholder loans, retirement contributions, inventory, rental property or investments while retaining a recognizable underlying structure.
The “straightforward 90%” names the design ambition. It is not a measured statistic about the proportion of returns supported by the current engine, and straightforward does not mean tiny or free of tax judgment.
Highly specialized international work, exotic ownership, unusual reorganizations, generalized crypto or derivatives, complex inventory systems and a comprehensive set of personal limitations are outside the current target. State returns and e-filing are not current product capabilities. The limitations page explains the boundary in context.
“Finished return” describes preparation and output: forms, supporting information and a saved package. It does not mean electronic transmission, taxpayer signatures, filing approval or IRS acceptance.
How do provenance and calculations work?
The original document, the software’s extracted proposal and the fact established by the preparer remain distinct concepts. Supported corrections retain original evidence and correction history. A parser-reading error is different from an error in the underlying books; more complex authority conflicts may need additional resolution rather than an automatic overwrite.
Unknown, known zero, not applicable and unsupported are different states. Missing history is not replaced with a convenient amount. Source acceptance also does not automatically answer every related tax question or election.
The tax core is deterministic: explicit established facts and rules produce reproducible calculations. Defined money handling, workpapers and “How calculated” explanations make behavior reviewable. Reproducibility supports testing; it is not a guarantee of exhaustive tax-law accuracy.
Saved preparations preserve the relationship between inputs, calculations and output. A later edit can make current output stale. Updating the return creates another preparation while preserving the earlier package as history. Forms, diagnostics and selected print output must refer to the same saved result.
See the evidence model and the architecture.
How is AI used?
Frontier models have assisted development through research, implementation, test creation, bounded agent assignments, fresh review and iteration under human direction. A lead integrates the work and resolves shared architectural questions. Browser and actual PDF inspection challenge what users see, alongside automated checks.
This is distinct from runtime extraction. The current documented parsers use supported structured inputs and bounded text-PDF layouts. AI-assisted development does not establish LLM extraction, OCR or arbitrary-format document understanding.
Models do not improvise the tax calculation or replace the preparer’s judgment. Independent model review is another engineering check, not external professional certification. The human tax professional retains responsibility for scope and product review.
The development story explains the successive Alpha questions and the difficult engineering behind the workflow.
What is Alpha 14?
Alpha 14 — human testing and broader operating-business coverage. The current public S-corp generation broadens the conventional business universe with bounded rental, inventory, capital-sales, vehicle, amortization, paid shareholder-loan-interest and accountable-plan-reimbursement support.
Synthetic examples make that progression visible: Juniper demonstrates the core path; Alder emphasizes multiple owners and basis; Cedarline combines richer operating-business features. These examples are development and review evidence, not client-use counts.
The Alpha history includes deterministic calculations, source intake, the professional workspace, Guided Preparation, source corrections, official forms, saved packages and broader owner support. New capabilities introduced obligations across prior behavior, history, output and review.
Alpha 14 is described as the human-testing generation. The site does not claim completed human acceptance, commercial-software equivalence, or filing qualification without corresponding evidence.
What comes next?
Form 1040 comes next. The individual engine is future work. It will use a household, person and tax-item model rather than expand the S-corp model into a universal object.
Evidence, explicit unknowns, deterministic calculations, workpapers, actual forms, saved history and professional control carry forward. Household relationships, income attribution, eligibility, credits and personal limitations need their own researched architecture.
A future structured shareholder package could connect corporate reporting with reviewed individual preparation without circular engine dependencies. Public APIs, a synthetic hosted showroom, broader integrations and comparison work are also directions. No launch dates or live integrations are implied.
Read the Form 1040 direction and the roadmap.
What is the open-source direction?
PrepReturns is private today and is being built with open source in mind. An eventual release could allow practitioners and engineers to inspect the implementation, modify workflows, build integrations, extend interfaces, contribute fixes or maintain a fork under the chosen license.
Those are intended future benefits, not rights already granted by an unpublished license. There is no public repository or download offered on this site. Modifying tax software would still require meaningful tests, review and professional responsibility.
How can someone collaborate?
We welcome conversations with tax professionals about testing and workflow, engineers about architecture and integrations, researchers about AI-assisted professional software, and tax-software companies about overlapping ideas and possible collaboration.
Specific examples are especially useful: an awkward preparation task, a source-authority problem, a review requirement or information that needs to move between systems. This website is not a taxpayer-data intake channel.
Explore collaboration or use the contact page to reach out through Trio Tax. The public site begins without analytics, advertising pixels, third-party embeds or a newsletter database. Privacy, security and terms describe the actual website and its boundaries.