VAT Engine journal

EU VAT, explained for builders

Technical and operational guidance for teams building VAT-aware products.

VAT Engine blog cover illustrating the fields that make a VAT calculation record explainable, including amounts, rate, date, source, and provenance.

Article · 11 min

What Should a VAT Calculation Record Actually Contain?

A VAT result is more useful when you can explain it later. Here is what a calculation record should preserve beyond the final tax amount.

By Vasyl Kyryliuk · Published Oct 8, 2026

VAT Engine cover comparing floating-point money arithmetic with integer minor-unit calculations for predictable VAT results.

Article · 13 min

Why Money Calculations Should Not Use Floating Point

Binary floating point is useful for many problems, but risky as a canonical money representation. Learn why minor units and explicit rounding make VAT calculations more predictable.

By Vasyl Kyryliuk · Published Oct 2, 2026

VAT Engine cover comparing VAT-exclusive pricing, where VAT is added to net, with VAT-inclusive pricing, where VAT is extracted from gross.

Article · 11 min

VAT-Inclusive vs VAT-Exclusive Pricing: The Math Developers Get Wrong

VAT-inclusive and VAT-exclusive prices require different formulas. Learn how to calculate net, VAT, and gross correctly without common rounding and percentage mistakes.

By Vasyl Kyryliuk · Published Sep 25, 2026

VAT Engine Journal cover illustrating how country, product, and transaction date feed into a VAT API to produce rate, context, and evidence.

Article · 7 min

Why a VAT API Needs More Than a Rate Lookup

A practical look at why production VAT APIs need more than a country-to-rate lookup: tax classes, transaction dates, pricing context, evidence, and reviewable decisions.

By Vasyl Kyryliuk · Published Sep 12, 2026