So, In Trumps defense(Oh god), Spicer was referring to a border adjustment tax that congressional republicans have already gotten behind. It's not actually a 20% import tax.
What's the difference. Serious question
I can't confirm whether there is or is not an import tax, but the former is quite a disastrous policy that will prevent the deductability of costs not incurred in the US. Many low-margin businesses will go under fast as written since they charge very low prices - If Wal-Mart buys something from China for $1.5 and sells it for $2, the tax is now on the full $2 sale (less wages, etc.). It's simply unsustainable. If it starts getting manufactured for $2.50 in the US, they can deduct the full $2.50, but need to charge a much higher price...you get the picture.
I was under the impression that the tariff was in addition to this, but that might be too outrageous.
Not to mention it does away with the interest tax shield. The Ryan tax plan is really quite terrifying.