I'm just wondering, whats the minimum age to file a w-9 form? I heard its can be any ages, if i'm correct?
There are no Age restrictions on filing or filling out a W-9, but I have to ask why? There are a lot of factors to consider here: How do your parents claim you? Do you make enough to report? Be careful with hours you work(report) -- as there are underage work limits and people can get in big trouble In General there isn't an age limit at which you can fine any tax form, but there are reasons why you should and shouldn't. Best bet would be to talk with your parents and have then talk to their accountant -- or Go to H&R Block and ask.
If you make over $7,000 you have to complete one no matter what age and report your income. If you are under age according to your state working laws, you must register your business under your parents' name(s). The reason networks make you complete this form is to prove where they are sending money at the end of the year to the IRS. Its more of a protection for Networks to not get audited and accused of money laundering.
I don't believe there is an age limit. However in the US you do have to be at least 13 to enter into a contract. And you are entering into a contract by joining affiliate networks.