Avoiding US Tax Withholding

Self-published authors i.e. those who publish straight onto sites such as Amazon, Smashwords, etc. without the help of a small press, will be aware that under United States tax laws 30% of US business incomes must be withheld unless appropriate documentation has been successfully submitted.
Non-US citizens may consider such a withholding does not apply to them because they do not conduct business within the US. However, you would be wrong. Though your business (that of being an author) is based in another country your product (books) are created and sold from US based business’s (Amazon, Smashwords, iBooks, Google Play Books, etc.). Consequently, your business, for tax purposes, is considered to be a US based one.
Prior to recent changes you needed to submit detailed documentation and probably apply for a US Tax Identification Number to recover the 30% withholding that companies were obliged to keep back from your royalty payments. Thankfully for us, the tax regulations have been eased recently by enabling authors to claim exemption under various treaty agreements. Nevertheless, it is still a fairly complicated field to manoeuvre through.
I publish all my books through Amazon (various international sites); Smashwords (which distributes to a number of retailers: iBooks, Barnes & Noble, Nook and many more including library listings); Google Play Books (they are not included in Smashwords distribution so I have my own account with them).  Each of these companies is obliged to request tax information from you.  Amazon and Google Play Books make matters a little easier by enabling such information to be submitted electronically.  Smashwords requires a physical form be submitted by post.
Amazon provides a questionnaire that, overall, is reasonably easy to complete nevertheless, there are elements that need to be clearly understood.  It is hard enough for most of us to understand the tax laws of our own nations.  It is harder still to understand those of a different country and culture.  Then there are the apparently simple differences which need to be comprehended otherwise the form may be rejected; apparently if this happens it takes a very long time to sort the matter out.  For example: date formats; US dates are written as month, day, year whereas UK dates are presented as day, month, year.  I understand even something as simple as this can cause the form to be rejected.
I have recently been revisiting this whole area, as well as others, in readiness for soon publishing a new novel and re-publishing a couple of existing books.  I discovered my existing tax completions require the 30% withholding.  It is a long and complicated matter to recover this from the tax authorities in respect of sales made in previous years.  I have therefore worked upon new tax submissions to take advantage of the treaty agreement with the UK so there will be no 30% withholding for future sales.  Even with the new, comparatively easier, forms I felt the need for guidance.  I was therefore very grateful to have come across the book I mention below.
Book Recommendation!
Beyond Frontiers: US Taxes for International Self-Published Authors by Marcela Martinez Millan.
I cannot recommend this book highly enough.  The author, a qualified tax advisor and a US Enrolled Agent; allowing them to represent taxpayers, has provided a most comprehensive guide for Non-US self-published authors.  She delves into all aspects whether you are publishing as an individual or corporation.  Gives guidance on what you need or do not need to apply for.  Explains about tax treaties and how to complete the various forms, highlighting where errors may unconsciously occur.
My above resume does not do justice to the book or the advice and guidance provided.  I TRULY CANNOT RECOMMEND IT ENOUGH.  To be frank, I think it is a publication all authors should avail themselves of.  Without hesitation I consider this warrants a five star (*****), if not higher, rating.  The author’s generosity in sharing all the advice is further complemented by the low price £0.99 ($1.44).  You will find links below to both the .co.uk and .com Amazon sites from which you may purchase the book.
Amazon.co.uk: http://www.amazon.co.uk/dp/B00OE2W2EW
Amazon.com: http://www.amazon.com/dp/B00OE2W2EW
Disclaimer: Other than having read the book and taking advantage of the guidance provided, I am in no way associated with the author and do not know them personally.