Get to an accountant with international experience.
Now for $60 I think you might be below the threshold, but you might as well find out about this stuff now rather than waiting.
When I first started practicing law (about 20 years ago), the firm I worked for had a client who died. In his will, he left one half of a mortgage payment that he had received to his nephew who was a resident of the Azores. The interest portion of a mortgage payment is taxable income to the recipient.
I don't remember the details, but basically the firm became a withholding agent, required by US law to withhold I believe 30% of the taxable income. We then needed to get him a tax payer ID (there's a specific office of the Internal Revenue Service ((IRS)) that deals with this) and he had to fill out a tax form each year.
You might want to check with some of our authors who have been published overseas. I believe they have tax liability in each country in which they are published. However, I'm not sure, which is why I suggest talking to an accountant with international experience.
By the way, further complicating this are various international treaties on taxes.
Remember, writing is fun!!!
Best of luck,
Jim Clark-Dawe