HM Treasury and HMRC have a vital role in ensuring that the multilateral assurance framework for Pillar One of the OECD reforms will meet Parliament’s desire for accountability and transparency. The 140 jurisdictions involved in the development and implementation of the reforms will have very differing cultures around the transparency with which tax systems operate and the approach to tax compliance activity, and differing levels of commitment to the reforms. The OECD reforms will be administered and enforced through a multilateral administrative framework which will change tax administration for multinational businesses and determine the approach to compliance actions. Success will depend on cooperation between countries hosting users and those hosting the businesses. HM Treasury and HMRC have a vital role in ensuring that the framework meets their objectives and the expectations of Parliament around accountability and transparency, and that these are reflected in the international agreement and the compliance regime. Recommendation 4: HM Treasury and HMRC should: • alongside the Treasury Minute response to this report, write to the Committee setting out their objectives for the development of the multilateral administrative framework, including audit arrangements, • ensure they propose assurance arrangements that will provide the UK Parliament with sufficient accountability and transparency to provide assurance that the Pillar One and Pillar Two reforms are operating effectively, and • set out robust forecasts of expected revenues when details of the new regime are agreed.