I went through a laborious process to fill out an application for an ITIN. All internet searches and advice from a few authors stated a certified copy of your (in my case, Canadian passport) from the issuer (in my case, The Government of Canada) was all that was needed.
My application was denied. I called the IRS on my dime, got a guy with a Bangalore accent and he told me rules had changed and I have to send the passport itself to Austin, Texas. Say what? Yes, I have to apply all over again. 6-8 weeks to process. So, I can't travel until you decide to send back my passport? Yes. Tough luck. Oh, and tough luck if it gets lost in the mail or at the Texas office.
So, what to do? There are options. All of them time-consuming and costly. It's not like I can nip down to the nearest U.S. Consulate to get my passport certified by a U.S. official, I live in Moosetown, Northern Canada. Hire a lawyer to do it? Or an accountant? Jesus, I'm not making enough money to do that.
Stick with Canadian e-pubs to eliminate the American mass of bullshit bureaucracy? Also an option. But there's not that many out there, most are American.
Go strictly the self-pub route? Apparently getting an EIN is way easier than ITIN. Sometimes only a phone call is all that's needed. However, an EIN is only good for self-pubbing, or so I have read on-line. Also, though they (IRS) take your word for it, you may at some point have to prove you are a company, even if you are the only employee. So be sure after you get the self-pubbing ball rolling, you do form a company that can stand up to legal issues from both sides of the border.
Check out this info HERE An attorney who spells it out quite plainly about an ITIN. Again, anything you read on-line should be taken with a grain of salt. (Including anything I have to say!!)
My Canadian passport expires in June, I have to jump through enough hoops to renew it. I am not worrying about my U.S tax status until I have to. But how and where I will publish will factor in my future submission decisions going forward. I may even consider self-pubbing to avoid this crap.
In the meantime, until a U.S. publisher actually withholds 30% of my income for tax purposes, I'm not going to worry about it. What to do when that happens? I hire an accountant and/or lawyer to fill out the appropriate U.S. tax forms and they can do the ITIN at the same time. Yes, this means I will wait many months for a refund from the IRS, and pay $$ to lawyers and accountants, but so be it. This is my own personal decision, its up to each author to decide how they wish to traverse this road.
It's relatively easy process to submit a manuscript and get published, (I don't mean the writing itself) and according to some, to self-pub. Just know there are implications to consider once you start making money.