From January 1999 to June 2011 he was the permanent under-secretary of State of the Ministry of Finance,[4] except a period from 2002 to 2003 when Lorents Lorentsen was acting secretary.
[5] It was in this period that he, along with Jens Stoltenberg and Karl Eirik Schjøtt-Pedersen authored the so-called budgetary rule, which regulates the usage of capital gains from the oil and petroleum sector and which would play a pivotal part of the economic policy of consecutive Norwegian governments.
[1] Known as a numerical "genius", he is also credited with providing the stable fiscal policy which Norway maintained throughout the Great Recession.
Eriksen served as Norway's official ambassador to the Organisation for Economic Co-operation and Development from 2011 to 2014, when he returned to the Ministry of Finance as a special adviser.
It was also revealed that the foreign minister Jonas Gahr Støre, his former colleague and alleged friend, had given him the very lucrative job without publicly announcing the vacancy.