At least a Branch Director.

VP, normally an unit DD in a branch.

HOD, normally an unit AD in a branch, but due to limited quota, some Hods are only given the title of Senior Officer in the unit if he or she has attained the SEO1 grade.

SH/LH, normally an unit officer. You will only attain the title of Senior Officer, provided you have attained the SEO1 grade.

GEO Officers, normally an unit officer. Therefore, those who can go HQ are normally officers with at least a CEP of P7 (SH/LH/St) potential.