The GloBE Rules provide for a co-ordinated system of taxation intended to ensure large multinational enterprise (MNE) groups pay a minimum level of tax on the income arising in each of the jurisdictions where they operate. It does so by imposing a top-up tax on profits arising in a jurisdiction whenever the effective tax rate (ETR), determined on a jurisdictional basis, is below the minimum rate of 15%.
The GloBE Rules comprise two rules - the Income Inclusion Rule (“IIR”) and the Undertaxed Profits Rule (“UTPR”).
Unterforen: Income Inclusion Rule (IIR) , Undertaxed Profits Rule (UTPR)

The STTR allows source jurisdictions to “tax back” where defined categories of intra-group covered income are subject to nominal corporate income tax rates below the STTR minimum rate, and domestic taxing rights over that income have been ceded under a treaty.