Hi and welcome to the Forum.
We're talking now about people coming to the Netherlands to find a job and work there.
The MVV (Machtiging tot Voorlopig Verblijf; in English, permission for a short-term stay) is a visa to enter the country if you are staying for more than 90 days; it also acts as a short-term residence permit. There are different types of MVV, some nationals also have to pass an Integration (Dutch society & language) exam as part of their MVV process.
You can apply for it in your own right (without a sponsor), but you could be rejected if they think you will struggle to find work or not find somewhere to live. If you are applying for a skilled migrant visa, then you must be sponsored and the sponsor must be registered with the IND.
The IND visa process can take up to 90 days (that's the official response), some can take even longer if the applicant does not supply the correct information the first time round as they will come back and ask questions. Skilled migrant visas can be much quicker (I've heard of 7 days), mainly because there is no Dutch language exam and the sponsor has done a lot of the legwork by offering a work contract, so it cuts out 2 Dutch Government Departments worth of checks. Including immediate family members (wife, husband and children) in this is an option, but can delay matters if further checks are needed.
The 30% tax rule is nothing to do with your visa; it's an arrangement between your employer (it's them that get the 30%, not you) and the Belastingdienst. One of the prerequisites is that you must be living at least 150 km outside the Dutch border at the time you are recruited, so if you think you can come to the Netherlands on an MVV, then look for a job where you will pay 30% less tax - forget it, it's not ever going to happen.
Household goods; coming from the US to Europe can be problematic for electrical items unless yours are switchable from 110v to 220v; the plugs are different. For conventional TV ether broadcasting, American TV's don't work in Europe (for the picture broadcast, the US uses NTSC, the Europeans use PAL). By the time you've finished faffing around with no guarantee of success, my advice is to do what my daughter did, she paid for a ticket that allowed her to bring 2 large suitcases on the flight, she left all the things she wanted to keep with us, then sold everything else. She bought 2nd hand from the local Kringwinkel to go in her first house. If you absolutely must bring your household with you, then find a local logistics company that ships personal goods US to EU, Google will be your friend there. The only time I've done it, the boss was paying, so I didn't care.
I should mention Covid; it's really screwed up local government with many people working from home; anything that involves a piece of paper has become almost impossible to deal with in many places, so be prepared for delays in those circumstances. The Dutch Government have a website that explains the requirements for entry, this will take you straight there. There is currently a requirement for vaccination before they will let you enter the country; you may have a different opinion, but telling everyone while you're in the queue at Schiphol is probably not the ideal time to inform everyone because they can turn you around and send you back to where you came from.
Hope this helps.
Cynic
Expat Team