Dutch law enables all legal residents to bring over their partner/spouse, minor children and dependent young adults (with a maximum age of 24) on the basis of family reunification Netherlands.
Family reunification Netherlands applies to the family members of all persons who are legally residing in the Netherlands. This is in short Dutch nationals and holders of Dutch residence permits.
EU citizens also are legal residents but their family reunification falls under a different (more lenient) regime of EU Directive 2004/38, but this is a different topic all together.
First requirement is the income requirement. This means that the sponsor must show she/he has sufficient and durable income. Sufficient means equal to Dutch minimum wage, which is in 2019 €1616 gross per month, excluding 8% holiday pay. For self-employed entrepreneurs this entails that their gross annual profit should be 12 times this amount plus 8%. Durable for an employee is either having at least a year contract (or more) at the time of applying, or when the contract is valid less than 12 months, showing she/he has earned the income requirement at least 12 months prior to the application. For entrepreneurs durable is having earned the income requirement at least 18 months prior to applying.
In addition, all adults who have to apply for the permit from their home country or country of legal stay will need to pass an integration exam at the Dutch embassy. This requirement does not apply to family members of US, South Korean, Japanese, Australia and New Zeeland. Also, family members of holders of work-related residence permits (employees and self-employed) are exempted from the mandatory integration exam.
Dutch law does not require marriage for family reunification, also non-marital and same-sex relationships are considered valid.
Once approved the applicant will be given a residence permit for five years under the condition that the family unit remains intact and the family income (that of the sponsor and/or spouse combined) stays in check with the minimum wage level. All family members will have unrestricted access to the labor market. Important to keep in mind is that persons who are not a family member of the holder of a work-related residence permit, will be required to pass integration exam here in the Netherlands within five years. This is not the exam taken at the embassy but a one which demands a much higher-level Dutch.