For:
Adsense?
YPN?
Google Affiliate Network?
CJ?
Clickbank?
Chitika E-Mini Malls?
Adbrite?
Kanoodle?
Zlio?
Kontera?
Intellitxt?
Ebay Affiliate Store?
Amazon Affiliate Store?
Microsoft contextual advertising?
ContextCash?
Searchfeed?
Tell me about the ones you know for sure. Thanks.
If these are US based companies, then yes, you need to fill out the forms. If you don’t, they either won’t let you work, or if they have already let work, will withhold 28% or 30% of the money being paid to you to ensure that the taxes are paid.