Working remotely from Belgium for a company in the Netherlands

I have a job offer from a Dutch software company (located and registered in Amsterdam), where I would be able to work remotely from Belgium most of the time (visits to the Amsterdam office a few days each month). I live and am registered in Belgium.

With my current employer (in Belgium), there is both the “social security contribution (NSSO)” and “paye tax on normal wages” that are paid by the employer. (They are about 40% of my gross salary).

It seems hard to find accurate information online about the tax rules in this situation. But there seems to be a 183-day rule, according to which I would be taxable in Belgium (and not in the Netherlands), if all these conditions are met:

– the employee stays in the country of employment for no longer than 183 days;
– the salary is paid by (or on behalf of) an employer who is not a resident of the country where the employee works; and
– the salary is not borne by a permanent establishment of the employer in the country where the employee works.

How to avoid double taxation if I live in Belgium, but work abroad?

About the second point, I’m not sure if “where the employee works” refers to where I’m located when working (from home), or where the company is for which I’m working. Also I’m not sure about the meaning of the third point.

On the salary offer that I currently received, the net salary would be about 78% of the gross salary, which would not be possible if the company pays Belgian taxes.

I was wondering if anyone knows / has experience with this situation, and what the tax situation would be. If social security and/or income taxes would be paid in the Netherlands or in Belgium, if they are paid by the employer (from the gross salary), or if I would need to pay additional taxes from the net salary. And if there can be the situation where I would have to pay the same tax two times in both countries.