Legal framework for exchange: Types of international agreement: The OECD/CoE Multilateral Convention on Mutual Administrative Assistance in Tax Matters: Periods covered
The OECD Multilateral Convention on Mutual Administrative Assistance in Tax Matters (MAC) provides that it applies to taxable periods beginning on or after 1 January following that year it was entered into force by a given jurisdiction. The period for which you can exchange will be the latest it entered into effect between the jurisdictions concerned.
There is a list on the OECD website showing when the MAC entered into force for each participating jurisdiction.
The MAC has effect in the UK for periods beginning on or after:
1 January 2009 for exchange with states who were signatories to the original Convention; and
1 January 2012 for exchange with jurisdictions who were signatories only to the Amended Convention.
It is possible, however, for Competent Authorities to mutually agree that they are happy to exchange information pertaining to periods before entry into force.
See IEIM200400 for more guidance on periods covered in tax agreements.