The 2006 IAU General Assembly has adopted the P03 model of Capitaine et al. (2003A&A...412..567C) recommended by the WG on precession and the ecliptic (Hilton et al., 2006, Celest. Mech. Dyn. Astron. 94, 351) to replace the IAU 2000 model, which comprised the Lieske et al. (1977A&A....58....1L) model with adjusted rates. Practical implementations of this new "IAU 2006" model are therefore required, involving choices of procedures and algorithms. The purpose of this paper is to recommend IAU 2006 based precession-nutation computing procedures, suitable for different classes of application and achieving high standards of consistency.