IOFCs (International Offshore Financial Centres) naturally generate significant amounts of professional work in support of the offshore companies and trusts that are set up in their territories. While some of this is performed by nationals of the IOFCs (creation of employment is evidently one of the reasons for a country to become an IOFC), much necessarily falls into the lap of expert foreign professionals, and IOFCs usually make it reasonably easy for such people to work.
Apart from 'offshore' professional activity as such, IOFCs are also an attractive location for professional firms offering their services internationally. Engineering and management consultancies are examples.
Whether connected with tax or not, professionals in IOFCs have many advantages. Of course they can usually take advantage of low local tax rates, which are often further reduced for employees of offshore entities or offshore partnerships; and there are often further concessions which add up to a highly favourable tax regime. Their services provided in high-tax jurisdictions will of course be deductible expenses locally, while there are often no withholding taxes on such payments. However, some high-tax jurisdictions have compiled 'blacklists' or 'greylists' of low-tax regimes operating what they consider to be 'preferential' tax systems, and apply punitive rates of withholding tax to outgoing payments.
The choice of an IOFC for a professional services company or partnership is highly dependent on the location of their customers, and their own existing residence. Therefore no short-list of possible IOFCs is offered. Click on Jurisdictions for full descriptions of some of the most interesting IOFCs.