The current agreement (SI1990/2590) entered into force on 31 December 1990. It generally has effect:
a) In the United Kingdom for
i) Income tax and Capital Gains Tax from 6 April 1991, ii) Corporation Tax from 1 April 1991, iii) Petroleum Revenue Tax from 1 January 1991.
b) In Italy from 1 January 1991.
However, in the case of shipping and air transport profits the new Convention has effect for accounting periods beginning on or after 1 January 1974.
If using the HMRC Intranet, the agreement can be viewed through the “New treaties/protocols in force” link on the sidebar. On the HMRC web-site, searching for “Treaties in force Italy” will provide a link to the treaty.
The text of the Tax Treaty can be found via https://www.gov.uk/government/publications/italy-tax-treaties