If you want to take a gig via YoungOnes, we assume you want to become self-employed. It is therefore a good idea to apply for a VAT ID (btw-id). Until you have a VAT ID, you are limited to three gigs without a VAT ID. To continue working via YoungOnes after the third gig you will have to apply for a VAT ID.
There are two ways you can apply for a VAT ID:
1. Through the Chamber of Commerce (Kamer van Koophandel in Dutch)
2. Through the Tax Authorities (Belastingdienst in Dutch)
It takes about two weeks before you receive your VAT ID if you apply for it through the Tax Authorities, but it is free. If you decide to do it through the Chamber of Commerce it usually takes less time but it will cost you around 75 euros.
You can find everything about applying for a VAT ID here.