08:58 Oct 15 

Temps are most often part of the overhead while contractors would probably be classed as contractors. However, a contractor could go out and "earn" his fee with consulting/services whatever, so always depends on the activity.

I did not pay further attention to BOOH earlier, but as they seem to have serveral branches, I'd give it a wild guess and say Branch Office OverHead - They are using English terms anyway, so this might be another evidence of it.

08:04 Oct 15 

This is a long shot, but could it be referring to temporary personnel from external firms who are not actually on the company's payroll and might therefore figure in the accounts as "overheads"? As I said, it's a long shot, I'm just exploring another possibility

07:09 Oct 14 

This mysterious "BOOH" is most probably an internal acronym used to designate a department or business unit. That said, this wouldn't change my assumption of "Overhead" being admin staff.

18:41 Oct 13 

Just come across another example, which seems to make it more mysterious as I have no idea what "BOOH" is...
"Allgemeine Korrespondenz in Deutsch, Fanzösisch (meistens nach Vorlagen) & Italienisch für alle xx Filialen der Schweiz sowie das Overhead-Personal (BOOH) nach Vorgabe des HR Direktors"

18:19 Oct 13 

Thanks. I think "administrative staff" is about right.

18:09 Oct 13 

As suggested below, I think this just refers to office/admin staff in general, and MIGHT refer to the head office more specifically (however, this is not supported by the context provided so far).

18:06 Oct 13 

It is, as I said, a category of staff. Here is another example: "Mithilfe bei der Erarbeitung & Einführung eines Mitarbeiterhandbuches für das Overhead-Personal, eines Starter – Packages etc. "