I’m not going to argue the morality (and stupidity) of paying lots of taxes, or the immorality (and smartness) of paying none, or little. I am a product of the Wall Street corporate game, and taxes are like death and divorce...unavoidable, unavoidable and very likely in that order.
The taxability of your income, derived totally by your business interests outside of Indonesia, and not associated with any business interests in Indonesia is questionable anyway, and reporting that activity would surely be shooting yourself in the foot.
If you play your financial game of trading stocks, bonds, or commodities here on Bali, only if on your computer, and with no Indonesian clients, be they locals or expats, your activities will soon enough be discovered...I assure you. However, the activities of your employees, associates, partners, or whatever you call them back in Holland, even though those activities advance your wealth base, are off of Indonesia’s radar...and you shouldn’t, even if they say you should, pay taxes here for that income.
Indonesia’s tax laws, as it applies to foreigners, is largely “activity” based. If your activity here, while living in Indonesia, produces income, even if “off shore” then it is in theory, taxable. Then again, depending on your visa status, even interest income on assets out of Indonesia without your activity can be taxable, but only if you report those assets...which is sometimes required to get the right visa.
My point is more based on the fact that you may eventually need to set up either a CV or PT company, to become “legit” and with an Indonesian partner for most any business enterprise you want to pursue while living in Indonesia. In that case, leave ALL tax related matters in the hands of your Indonesian partner.
Also, keep in mind that any business or income related activity of a foreigner who is not on the proper visa designed for that specific business activity, (and there are several different types of business visas) violates immigration laws. While the tax people may currently lack teeth, the immigration folks do not, and it is not unusual here in Indonesia that a suspected tax evasion scheme of a foreigner is turned over to immigration for their resolution...meaning possible deportation or at minimum, some serious fines.
Sorry that I can’t recommend any really good attorneys in the southern part of Bali. No doubt there are many, given the level of foreign investment down there. Again, good luck and there is no sweat off my back concerning your tax concerns. Hell, I hate the idea of sending any money back to the states for GW Jr. to use in his war machine!