As you might have figured out, the days of tax-free online shopping are over. The Supreme Court’s South Dakota vs. Wayfair decision last June threw out the decades-old exemption for retailers who didn’t have a physical presence such as a store or distribution center in a state.

South Carolina is among more than 30 states now requiring out-of-state retailers to collect sales tax, and 27 states where shipping charges are taxable, too. Already complicated sales tax laws are constantly evolving, so the software online retailers use to help them comply has to interface with tens of thousands of tax jurisdictions nationwide.

While the high court’s decision helped secure parity for local bricks-and-mortar retailers, it can trip up consumers, especially in the 29909 ZIP code, which parts of greater Bluffton share with Okatie and neighboring Jasper County.

During the holiday shopping season, this writer made online purchases from retailers such as Neiman Marcus, with no presence in the state; Macy’s; Belk and Stein Mart, the latter of which has stores in Bluffton and Hilton Head, and was charged sales taxes by all.

Many online retailers ship from fulfillment centers, so multiple-item orders arrive staggered, and depending on the payment method, the customer might be billed when the order is placed or when it ships. Preferred credit cardholders usually get free shipping and the option of making returns and exchanges at the local store.

This is why it took several weeks to figure out I’d been overcharged sales tax on every one of 25 clothing and accessory items purchased from in November and December, many of which were returned to the store, then re-ordered online to get the right size.

As a preferred cardholder, my shipping was free, and Stein Mart’s customer service credited my account to honor its lowest sale prices on the exchanged items. But representatives were stymied when asked how sales tax charges were computed.

Following three weeks of calls and emails, a supervisor in Stein Mart’s e-commerce division wrote that “after further research, you were charged the correct taxes.” His email stated “6 percent tax for the destination state (S.C.) and 3 percent for the destination county (Jasper).”

That would be fine, except that I, along with everybody else residing in the original Sun City Hilton Head, live in Beaufort County. It took only a casual conversation with a neighbor to find out that she too had been overcharged sales tax on her online purchases.

Eventually, we each had our accounts credited.

My current statement reflects $14.79 in credits, issued in increments from 66 cents to $6.50 for overcharged sales taxes. The supervisor advised that my zip code plus-four (29909-6083) be entered on all future orders.

To put it in perspective, paying an extra 3 percent in sales tax is more than the 2.8 percent increase in Social Security benefits for 2019. Online buyers, beware: Don’t get nickel and dimed into paying more taxes than you owe.

Freelance writer Pam Gallagher was a copy editor at USA Today and a staff writer and fashion editor for the Asbury Park (N.J.) Press.