23 August 2026 · ETR
Effective Tax Rate & the Top-up
The DMTT top-up is the gap between the 15% Pillar Two floor and your jurisdictional effective tax rate (ETR): covered taxes divided by GloBE income, blended across every UAE constituent entity of the group. GloBE income starts from accounting profit with prescribed adjustments, and a substance-based income exclusion is applied before the top-up is charged, stripping out a routine return on payroll and tangible assets so only "excess" profit is exposed. If the UAE ETR comes out below 15%, the shortfall percentage is applied to that excess profit: a group with, say, AED 400 million of UAE GloBE income and AED 24 million of covered tax has a 6% ETR, a 9-point gap to close, and a real cash top-up to calculate and pay once the substance carve-out is applied.
Exiloz Management & Tax Consultant · Dubai-based FTA-focused advisory · VAT, corporate tax & accounting
How the ETR is built
The DMTT calculation is deliberately jurisdictional: every UAE constituent entity of the group is blended into a single effective tax rate, rather than being tested company by company. This matters because a profitable, lightly-taxed entity cannot be isolated and taxed at 15% on its own; it is averaged together with every other UAE entity's income and tax, so a mix of 0% free zone income and 9% mainland income within the same group produces one combined UAE ETR.
- ETR = covered taxes รท GloBE income for the UAE.
- GloBE income starts from financial accounts with adjustments.
- A substance-based exclusion removes a routine return.
- Top-up applies to the excess profit above the carve-out.
- The calculation blends every UAE constituent entity into one rate.
- Covered taxes include UAE corporate tax and certain other qualifying taxes paid.
- Losses and timing differences can affect the GloBE income adjustments.
- The same mechanics repeat every financial year the group stays in scope.
Closing the gap to 15%
Once the UAE ETR and the substance carve-out are known, the arithmetic itself is simple: multiply the shortfall percentage by the excess profit left after the carve-out. What makes the final number hard to predict in advance is that both inputs (the blended ETR and the size of the substance exclusion) depend on data gathered from every UAE entity in the group and standardised to GloBE definitions. A qualifying UAE DMTT also takes priority over a foreign IIR or UTPR trying to tax the same shortfall, so getting the UAE figure right protects the group from being taxed twice on the same profit.
- Top-up % = 15% minus the UAE ETR.
- Applied to excess profit after the substance exclusion.
- A DMTT that meets the QDMTT standard takes priority globally.
- Accurate GloBE data is the hard part, not the arithmetic.
- The substance exclusion rewards real UAE payroll and tangible assets.
- A larger UAE workforce and asset base can meaningfully reduce the top-up.
- The result should be modelled well before the return is due, not after.
Seeing the calculation with real numbers
Take an in-scope group whose UAE entities together report GloBE income of AED 400 million for the period, with AED 24 million of covered taxes actually paid. Dividing 24 by 400 gives a jurisdictional ETR of 6%, nine percentage points short of the 15% floor. If the substance-based income exclusion strips out AED 80 million as a routine return on the group's UAE payroll and tangible assets, excess profit falls to AED 320 million, and the 9% shortfall is applied only to that AED 320 million, a top-up of roughly AED 28.8 million. These illustrative figures show why two groups with the same headline UAE profit can owe very different top-up amounts depending on how much genuine payroll and fixed-asset substance they carry in the UAE.
- ETR of 6% on AED 400 million of GloBE income leaves a 9-point gap to 15%.
- The substance carve-out reduced the taxable excess from AED 400m to AED 320m.
- The resulting top-up in this example is approximately AED 28.8 million.
- More UAE payroll and tangible assets directly shrinks the top-up exposure.
Related guides
Frequently Asked Questions
For groups modelling their UAE top-up before it hits a return.
How is the effective tax rate calculated?
Covered taxes divided by GloBE income, blended across all UAE constituent entities of the group for the period. GloBE income is not simply taxable income under the UAE corporate tax law: it starts from accounting profit and applies a separate, internationally standardised set of adjustments, so the ETR used for DMTT purposes can differ from the group's ordinary UAE corporate tax rate.
What is the substance-based income exclusion?
A carve-out that removes a routine return on the group's UAE payroll costs and tangible assets before the top-up is calculated, so the DMTT targets excess profit rather than the ordinary return on real economic activity. The larger and more genuine a group's UAE workforce and asset base, the smaller the excess profit exposed to the 15% test, a deliberate design choice to avoid penalising real substance.
Does a 9% UAE rate mean no top-up?
Not necessarily. Incentives, exempt income, or the 0% Qualifying Free Zone Person rate can pull the blended UAE effective tax rate below 15% even though the headline corporate tax rate is 9%. Because the calculation blends every UAE entity together, a mix of 0% free zone income and 9% mainland income is exactly the kind of profile that commonly produces a top-up.
What counts as "covered taxes"?
Covered taxes generally include UAE corporate tax actually paid or accrued on the relevant profit, along with certain other qualifying taxes recognised under the GloBE rules. Getting this figure right matters as much as GloBE income itself, since the ETR is a ratio of the two, an error in either number changes the calculated top-up.
Can the top-up change from year to year?
Yes. Both GloBE income and covered taxes are calculated fresh each financial year, so the UAE ETR (and any resulting top-up) can move significantly as profit, incentive use and the substance carve-out change. Groups close to the 15% line should model the calculation every year rather than relying on a prior year's result.
Do free zone incentives make the top-up worse?
They can. Because 0% qualifying free zone income lowers the blended UAE ETR, groups that rely heavily on free zone incentives are more likely to see a DMTT top-up than groups earning most of their profit at the standard 9% rate. This does not mean free zone status should be abandoned; it means the DMTT impact needs to be modelled alongside the incentive, not assumed away.
Can Exiloz model our top-up?
Yes. We build the full GloBE ETR calculation for your UAE entities (GloBE income, covered taxes, the substance-based exclusion and the resulting top-up) using the same mechanics as the worked example above, so the DMTT figure is known and defensible well before your return is due.
Model your top-up before you file
Exiloz builds your GloBE ETR calculation, applies the substance-based exclusion correctly, and quantifies any UAE DMTT top-up so the number never arrives as a surprise.