Printful will always charge if it calls for it to be. Technically (U.S.) if you are under 20k a month your exempt from having to charge anything. But that doesn't mean that Printful or your other suppliers aren't, they still have to charge sales tax supplying to you because that's the service they are providing you. I'm not a tax expert at all and for the most part i just add the tax into my price because I have no way of telling whether a customer is in a zone that calls for it until after I sell something. Not to mention if it is the European Union and VAT is involved then things get complicated. This best thing to do is register your company so it has a tax ID then you can apply for exemptions. I believe if you are under 80k or something for the European Union then you are exempt from VAT tax but can only apply for this if you have Tax ID. Now with that said Printful still has to fulfill its tax obligations and will charge you a VAT tax or U.S. tax if it calls for it. For example if you use their services in the European Union and the sale is in the European Union but your company is in the U.S. then you will be charged not only from Printful but for example Etsy will also charge you. because they both still have to pay. Lost yet, I know it gets complicated just know you need to have enough in your prices to cover this and if not covering it in the one sale then covered over multiple sales that don't get charged these taxes. Hope this helps you at least narrow things down a bit. And if your seriously worried about loss or getting in trouble then hire a tax accountant they will know exactly what to look for after seeing your data and if you are a small operation they won't charge you much to get you set up.