www.leaseaccounting.org
A code-first reference for lessee lease accounting under ASC 842 and IFRS 16 — right-of-use and liability measurement, deterministic amortization schedules, disclosure reporting, and the Python that makes all of it auditable.

leaseaccounting.org is a specialized, deeply-linked knowledge base that treats lease accounting as an engineering problem. Every guide carries two layers at once:

• a compliance layer — the exact ASC 842 and IFRS 16 codification paragraphs, the formulas rendered in real math, the disclosures, and the audit controls; and
• a code layer — runnable, decimal-precise Python that implements the calculation, with the precision, day-count, and reconciliation edge cases that break naïve implementations.

It is written for the people who actually have to make the numbers tie out: corporate accountants, lease-operations teams, FinTech developers, and Python automation engineers.

• Accountants & controllers — trace a figure on the face of the financials back to the standard that requires it, with worked examples and disclosure templates.
• Auditors & compliance teams — see the controls, the reconciliation invariants, and the failure modes that trigger qualifications.
• Engineers building lease software — copy patterns that use decimal.Decimal, lock the discount rate, and close every schedule to exactly zero.

The site is organized into four areas that follow a lease from raw contract to audited disclosure:

• Core architecture & ROU models — measurement precedence, lease-term boundaries, discount-rate determination, right-of-use asset frameworks, classification, and modification accounting.
• Document extraction & clause parsing — PDF/DOCX ingestion, OCR, NLP clause tagging, payment-schedule normalization, multi-currency handling, and async portfolio processing.
• Liability amortization & schedules — present-value logic, the effective-interest method, automated schedule generation, materiality thresholds, and precision troubleshooting.
• Disclosure & financial reporting — maturity analysis, weighted-average rate and term, variable and short-term lease cost, and the lease-liability rollforward.

Every page cross-links to the concepts it depends on, cites the governing paragraphs, and ends with a worked Python example.

• Standards-accurate — real ASC 842-20 / ASC 842-10 and IFRS 16 references, not hand-waving.
• Decimal-exact code — money is never a float; schedules reconcile to 0.00 and re-derive byte-for-byte.
• Original diagrams — hand-authored, theme-aware SVGs that adapt to light and dark.
• Fast & accessible — a static, offline-capable progressive web app that passes WCAG 2 A/AA and a mobile performance budget.

• Eleventy static site generator (Nunjucks + Markdown)
• KaTeX for server-rendered math (self-hosted, no external requests)
• Hand-authored inline SVG diagrams and structured JSON-LD on every page
• Deployed as a Cloudflare Workers static site (installable PWA, offline fallback)

npm install
npm run build     # build the static site into ./_site
npm run serve     # local dev server with live reload

Start at www.leaseaccounting.org and follow the cross-links — every calculation page points to the concepts upstream and downstream of it.

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