SPOD will begin charging Sales Tax on the 6th April 2020 in Maryland.
We apply your sales tax rate based on the customers zip code. The tax rate is different in each state, and within each state, it varies by county, city, and district.
Usually sales tax is based on product + shipping cost, but there are exemptions.
Find more information on this question here: https://www.avalara.com/us/en/blog/2018/11/how-to-handle-sales-tax-on-shipping-a-state-by-state-guide.html