HSM visa + contractor clients: should this be "resultaat uit overige werkzaamheden" or should I register with KVK?

Hi everyone,

I'm looking for some guidance because I'm getting mixed impressions after reading online.

My situation is:

• I live and work in the Netherlands on a Highly Skilled Migrant (HSM) permit and I have a full-time job with my sponsor.
• Besides that, I have two contractor clients (one in another EU country and one in the US), both for software development.
• The work is fully remote and they're paying me to my bank account
• My accountant (Blue Umbrella) has been filing this income as resultaat uit overige werkzaamheden for the past few years. They have all my invoices and payment records and are aware of the clients.
• I have not registered with the KVK.
• The contractor income varies significantly from year to year, and I'm genuinely not sure whether these engagements will continue, as they could end at any time.

My questions are:

1. Is it realistic for this type of income to remain classified as resultaat uit overige werkzaamheden, or would it normally be considered winst uit onderneming?
2. Is KVK registration likely to be required in a situation like this?
3. Does the uncertainty of the contractor work (it may stop soon) make any difference?
4. Could not registering with the KVK have any implications for a future permanent residence application, assuming all income has always been declared correctly and taxes have been filed?

I'm not looking for advice on how to avoid taxes, I've always declared all income already. I'm just trying to understand whether my current setup is compliant or whether I should proactively change something.

I'd especially appreciate hearing from people who have been in a similar situation.

Thanks!