Professional-grade treaty reasoning for cross-border U.S. tax cases

International U.S. Tax Intelligence

Lexium is a professional-grade treaty analysis framework that structures complex cross-border cases into a defensible workflow: facts → rule → treaty articles → judgment — with CPA review controls.

Know the controlling treaty article, test the exposure, and document the reasoning.
Standalone product roadmap: Lexium is being developed toward a standalone professional tool. Early access is available via pilot engagements.

Who Lexium is for

Lexium is designed for complex cross-border profiles where treaty selection, income characterization, and entity structure drive real audit risk.

Advisors

CPAs & tax teams

Standardize treaty reasoning across cases, enforce review, and create a defensible workpaper trail.

Individuals

U.S. persons abroad

Employment, consulting, pensions, and passive income across jurisdictions with reporting exposure.

Complex structures

Founders & entity owners

Entity involvement triggers PE and attribution analysis and often requires CPA review.

What Lexium does

Lexium produces deterministic treaty outputs you can defend: controlling articles, exposure testing, and review controls — not generic advice.

Treaty engine

Primary + secondary articles

Identifies the controlling treaty article and surfaces secondary exposure (PE, business profits, overrides).

Risk controls

CPA review flags

High-risk patterns automatically route to CPA review: entities, PE indicators, mixed income, special articles.

Workpapers

Audit-ready trail

Standardized documentation: sanitized facts, rule rationale, draft analysis, and approval attribution.

Cross-border reality

Multi-income profiles

Handles multiple income types and characterizations in one year without collapsing to a single conclusion.

Professional workflow

Case tracking

Cases move through intake → analysis → CPA review → finalized with consistent status discipline.

Future product

Standalone roadmap

Lexium is being built toward a standalone professional tool; pilots are available now.

How it works

A simple workflow designed to stay consistent under scrutiny.

1
Structured intake

Capture the facts that materially affect treaty outcomes.

2
Rule selection

Apply the jurisdiction-specific treaty selector rule.

3
Article outputs

Primary article + secondary exposure surfaced automatically.

4
Draft reasoning

Document the rationale and tested exposure in a standard format.

5
CPA review

High-risk cases are reviewed, approved, and finalized with attribution.

Jurisdictions currently supported

Live coverage today. Additional jurisdictions added selectively.

Italy
France
Spain
Switzerland
United Kingdom
Germany
Canada

Schedule a call

Discuss a cross-border case, a pilot engagement, or the Lexium product roadmap. Book a time that works.

Lexium is a professional analysis and reasoning framework. It is not consumer tax software and does not provide automated tax filings or legal advice.