The Sales Tax Permit is a permit that your State issues you that gives you the right to collect and remit sales tax in your State. Anyone in business should already have this permit.

If you do not have a Sales Tax Permit, click here, then click on your State to apply for one

Beware! There are scams out there that would love to sell you a sales permit at an exorbitant price. Be sure you are dealing with your State government site!

For info on each State, this resource may help:  
A State-by-State Guide to Seller’s Permits

This info is also in this FAQ:
POD Overview

Merchant ID Number

Using the POD service and Stripe, keep in mind that you are the merchant for your artwork and products. 

When submitting the form for your State's Sales Permit and are asked for a merchant account number,  use your Stripe merchant id number.

A merchant ID number—commonly called a merchant number or MID—is a 15-digit numerical identifier used to facilitate credit and debit card payments for your business

For more info see: 
What merchant identification numbers are, and how to find yours

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