Changelog

First release.

Added#

• vat(), add() and extract() for one amount, with extraction done as gross × rate ÷ (1 + rate) rather than gross × rate — the commonest mistake in this arithmetic, which overstates the tax by the rate squared.
• invoice() for many lines, each able to carry its own rate and treatment, with a breakdown by rate and treatment because that is what a tax return asks for.
• Integer minor-unit arithmetic throughout: every amount becomes whole fils, halalas or paisa on arrival, so a thousand lines of 0.07 come to exactly 70.00. Results carry minor alongside the strings so the next sum does not start from a parse.
• rounding_level: 'line' | 'total', because taxing each line and summing gives a different answer from taxing the total — 0.20 against 0.15 on ten lines of 0.30 — and authorities specify which.
• rounding: 'half-up' | 'half-even' | 'down' | 'up', with half-up going away from zero as tax rules specify.
• Rates with effective dates for the UAE, Saudi Arabia, Bahrain, Oman, Pakistan, Egypt and Jordan, so rateFor('SA', '2019-06-01') is 5% and today is 15%. historyFor() returns the changes on record.
• null rather than 0 for Qatar and Kuwait, which have announced VAT and not introduced it — an invoice there carries no tax line at all.
• Treatments for zero-rated, exempt, out-of-scope and reverse charge, kept distinct through the breakdown even though all four are 0%.
• Per-currency decimals: two for AED, SAR, PKR and EGP, three for BHD, OMR, KWD and JOD.
• Quantities and per-line discounts, applied before tax.
• Amounts refused rather than guessed at: a thousands separator or Arabic-Indic digits throw instead of silently parsing to something wrong.
• 2.0 kB gzip, zero dependencies.