This is my issue as well: I have a profitable, single owner LLC in the USA, selling US made goods within the USA only. File my taxes in the USA. Just moved to the NL in 2018 and having no luck in finding someone helping me to file my Dutch taxes. I got my resident status, BSN number, and health insurance. Never got the M-Formulier from the Belastingsdienst.
Should I order it myself, file my US income as 'income' only without giving the source? In addition get the 'Verklaring belastingplicht woonland' filled out and signed by the IRS in the States?
At this point I don't even care if I have to pay more taxes than I should. I'm worried of getting into trouble with the Dutch authorities by doing nothing.