Lesson 4 — Excise Categories: three mechanics
An excise category is the rate engine. It answers one question — how is the tax on this good computed — and the module supports three answers. Getting the mechanic right matters more than getting any single rate right, because a wrong mechanic produces a number that is quietly wrong rather than obviously missing.
| Mechanic | What it multiplies | Which goods |
|---|---|---|
| Ad valorem | A percentage of the excise price | Tobacco, electronic smoking devices, their liquids, energy drinks |
| Volumetric | A flat amount in dirhams per litre | Any good taxed by volume at a single rate |
| Tiered volumetric | A dirhams-per-litre rate chosen per item from its sugar figure | Sweetened drinks |
The click path. Open Accounting → Configuration → UAE Excise → Excise Categories, which needs the Manager level of the UAE Excise privilege. The seeded defaults put tobacco, electronic smoking devices, their liquids and energy drinks at 100% ad valorem, and put carbonated and sweetened drinks together on the 2026 sugar tiers — 0 to 5 g/100ml exempt, 5 to 8 at AED 0.79 per litre, 8 and above at AED 1.09 per litre. Those seeded tier figures match Cabinet Decision 197/2025 Art. 10(1), including the AED 0.79 that the FTA web page gets wrong.
A tiered category holds no single rate, and that is the point. All three drinks in Lesson 2 sit in the same category, and they came out at AED 1.09, AED 0.79 and AED 0 per litre. The category supplies the ladder; the product supplies the rung, through its own Sugar (g/100ml). An ad-valorem category behaves in the opposite way: one rate for every product in it, with the differences between products coming entirely from the Excise Price Register in Lesson 5, never from the category.
The failure mode: the right product in the wrong mechanic. Falcon Energy is an energy drink — 250 ml cans, 11.0 g of sugar per 100 ml, 7,200 units released in January, and an excise price of AED 9.50 that Lesson 5 derives. Correctly categorised as ad valorem at 100%, it carries 7,200 × 9.50, which is AED 68,400.00. Dropped into the sweetened-drinks category instead, the same product computes 7,200 × 0.25, which is 1,800.00 litres, at the top tier rate of 1.09 — AED 1,962.00. The declaration confirms, the return balances, and the liability is understated by AED 66,438.00.
Notice why that error survives review. It does not produce a blank, an error message or a zero; it produces a small, tidy, arithmetically correct number in the right currency on the right line. The only defence is the classification discipline in Lesson 3 — check the mechanic on the category before you check the figure on the line, and reconcile your excise-good product list against Article 2 whenever the catalogue changes.