The National Executive Council is responsible for the overall running of the Union and for implementing the policies adopted at the Union's National Delegate Conferences - which meet every two years. The National Executive Council is composed of four National Executive Officers and approximately thirty ordinary members. Under the Rules of the Union, the size of the Executive may vary in response to any growth or reduction in the Union's total membership.

National Executive Council members are nominated by Sectors within each Division on the basis of one member for every 9,000 financial members in the Division. Elections to the positions take place at the Biennial Delegate Conference of each Division. Those going forward for the election to the National Executive Council must meet certain criteria concerning length of Union membership as laid out in the SIPTU RULE BOOK

The Union's five National Trustees - rank-and-file members, who are elected by each Division, are allowed to attend Council meetings as observers.

The National Executive Officers, Council members and Trustees are elected for six-year terms; these office-holders may seek re-election. The National Executive Council meets at least once a month to hear progress reports from the Union's senior officials, to devise plans and campaigns and to decide on the Union's response to recent developments. The National Executive Officers supervise the work of the Union's full-time staff in accordance with the decisions taken by the National Executive Council.