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Impact of OECD International Tax Reform Plan


On 8 October 2021 the OECD updated its statement setting out the framework for international tax reform. The two-pillar plan will require the UK and other OECD members to make major changes to their domestic tax law over the next couple of years.

What is the two-pillar plan?

The two-pillar corporate tax reform plan forms part of the OECD's project tackling base erosion and profit shifting (or BEPS).

Pillar One aims to align taxing rights more closely with the location of customers or users. The Pillar One rules will reallocate a portion of the profits of a multinational enterprise (MNE) to market jurisdictions where the MNE has a substantial engagement in that market, regardless of whether it has a physical presence there.  This measure will only apply to the largest businesses in the world - MNEs with annual global turnover above €20bn (reducing to €10bn in no earlier than seven years) that have a profitability threshold above 10% and do not fall within an exclusion.

There are two main elements to Pillar One: Amount A and Amount B. Amount A is the proportion of "residual profit" (profit in excess of 10% of revenue) allocated to market jurisdictions which meet a nexus test. Amount B is an agreed return for related parties carrying out baseline marketing and distribution activities.

Pillar Two seeks to establish a global minimum corporate tax rate through a set of interlinked rules.  The rules will apply to MNEs that meet a €750m turnover threshold (determined under the BEPS country by country reporting rules), and do not fall within an exclusion. 

Global anti-base erosion rules (GloBE rules) will impose top-up taxes where the effective rate of tax of a MNE in a jurisdiction is below the global minimum corporate tax rate (15%). The global minimum corporate tax rate will be effected by two rules: the income inclusion rule (IIR) and the under-taxed payment rules (UTPR). 

The IIR taxes a parent entity on its proportionate share of a low-taxed constituent entity’s income (similar to a CFC charge). Where top-up tax is required but the IIR does not apply (for example because the only parent is located in a low tax jurisdiction), the UTPR will apply.  The UTPR imposes top-up taxes on other group entities that meet various criteria.

There will also be a subject to tax rule (STTR) which will allow source taxation (for example, withholding taxes) on certain cross-border related party payments that are subject to tax below a minimum rate (9%).

What was announced in October?

OECD members have now agreed the remaining key figures relevant to the application of the new rules:

  • The proportion of in-scope MNE's residual profit that local jurisdictions will be able to tax under the Pillar One Amount A mechanism will be 25%;

  • The global minimum tax rate will be 15% (in July the OECD had said "at least" 15%); and

  • The minimum tax rate for the STTR will be 9%.

The OECD also has confirmed that the global minimum tax rate will not apply for jurisdictions where the MNE has revenues of less than €10m and profits less than €1m.

Implementation timetable

The revised OECD statement included an outline implementation timetable.  The remaining detail will be published by the OECD in two tranches: (1) Pillar Two GloBE model rules and a model STTR treaty provision in late November; and (2) Amount A model domestic legislation and commentary and a multilateral convention (MLC) in early 2022.  There will be a signing ceremony for the MLC in mid-2022 andit is expected to enter into force at some point in 2023 (once ratified by a "critical mass" of jurisdictions).  Most of the Pillar Two measures are also expected to enter into force in 2023 with the detail of the Pillar Two implementation steps due to be confirmed by the end of 2022.


  • 8 Oct 2021

    No new digital services taxes allowed

  • Late Nov 2021

    • GloBE model rules
    • STTR model treaty
  • Early 2022

    • Model Amount A domestic legislation
    • Amount A commentary
    • Amount A MLC and explanatory statement
  • Mid 2022

    • STR MLI
    • Amount A MLC signing ceremony
  • End 2022

    • Finalise Amount B design
    • GloBE implementation framework published
  • 2023 

    • Amount A MLC comes into force
    • Pillar 2 GloBE rules come into force (except UTPR)
  • 2024

    UTPR comes into force

Although we had expected details of the remaining issues to be published in full this month, the fact that the core elements of the plan have now been agreed, together with the ambitious implementation timetable, shows that this project continues to move with considerable momentum.

What might we see in the Autumn Budget?

  • A commitment to implement the two-pillar plan into UK domestic law. In June 2021 the Chancellor spoke of the UK as having been "pushing for" these "seismic tax reforms", meaning that it is likely that the UK will want to be seen to be one of the early adopters of the two-pillar plan.

  • A commitment to phase out digital services tax (DST). Before DST was introduced, the UK government estimated that DST would yield £400m of revenue per annum by 2021/22. It will be interesting to see the impact of the OECD two-pillar plan on the UK Exchequer. As the UK has been advocating for this reform, the UK government presumably thinks there will be an overall positive effect despite the loss of DST revenue.

  • Possibly an announcement of how and when the UK government intends to legislate for the changes. Given the anticipated timetable, this may need to be outside of a finance act.

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