Trident Replacement Cost

March 2014

The expected cost of the Trident replacement programme, in terms of design and construction of submarines, was set out as £11-12 billion in 2006, with additional costs for warhead development and other infrastructure, making the total £15-20 billion. This has since been revised to take account of inflation, described as the cost in ‘out-turn prices’ and is as high as £25-30 billion for the whole project.

These original  figures were set out in the original December 2006 White Paper.

The development of the replacement submarines was broken down into three phases, concept, assessment and construction. The concept phase lasted from March 2007 (House of Commons vote) to May 2011 (publication of Parliamentary Initial Gate report). The assessment phase will last from May 2011 (Initial Gate) to the Main Gate decision, currently expected to take place in 2016 (as stated in the Strategic Defence and Security Review in 2010, and again in the Initial Gate report). The Main Gate decision is where authorisation for construction

The Initial Gate report stated that £900m had been spent by May 2011 and a further £3 billion would be spent by Main Gate.

Page 8 of the report reads:

4.3 Cost of the Next Phase. Since Parliamentary approval to replace our nuclear deterrent in 2007 the MOD has spent around £900M (at outturn prices). 

On the Concept Phase of initial submarine design work, the progression of the CMC work with the US and the investment in design, programme management and construction skills that will allow us to build the submarines effectively. Between now and Main Gate in 2016 (the decision point at which contracts for building the submarines will be placed) we expect to spend a further £3Bn at outturn prices on the work plan set out in section 4.1 (including the long lead items previously highlighted). We therefore expect to have spent some £3.9Bn on reaching Main Gate, or around 15% of the outturn cost of the submarines (based on a four boat fleet). This is in line with the MOD’s approvals guidance, whichadvises that programmes should expect to spend 15% oftheir budget in reaching Main Gate. This ensures that programme risks are understood and managed, build contracts are based on suitably mature designs, and there is confidence that sufficient preparation has been made toHMS Ambushdeliver to time and cost.

The Update to Parliament produced in December 2013, stated, Expenditure to the end of the financial year 12/13 amounted to £415M, bringing the overall sum spent on the Assessment Phase to £730M, which is in line with plans set out in the Initial Gate Business Case. The forecast cost to Assessment Phase completion remains within the £3Bn envelope approved in April 2011.


Read the 2013 Update to Parliament