The trend of more counties and cities, imposing sales taxes continued in 2019 in the wake of the Supreme Court’s 2018 decision in South Dakota v. Wayfair Inc., according to a new report.

Fifteen counties and 62 cities added sales taxes in 2019, according to the report from sales tax technology developer Vertex, which also discusses the many post-Wayfair modifications creating new challenges for companies, including the risk of retroactive tax collection.

There was only one state sales tax change in 2019. On April 1, Utah increased its rate from 4.700 to 4.850 percent. Over the past decade, the combined number of new and changed sales and use tax rates since 2010 has been 5,733, an average of 521 per year.

However, there has been a continuing increase in the number of states expanding their sales taxes to online transactions in the aftermath of the Wayfair decision, with 43 states plus the District of Columbia enacting economic nexus laws. That meant the number of states requiring remote sellers to collect and remit sales taxes based on economic nexus more than doubled last year.

By the end of 2019, 37 states (including D.C.) had enacted marketplace facilitator laws that require tax collection and remittance on behalf of third-party sellers. The rules aim to protect small and midsized businesses from onerous sales tax collection requirements. That’s one of several aspects of the Wayfair decision that’s supposed to protect small sellers (along with economic thresholds, exemption from retroactive tax collection, and a general obligation to make sales tax less burdensome). But while most states have stuck to those principles, some have not.

For example, some states are trying to collect retroactive sales tax from out-of-state online merchants, while also proposing to extend retroactive collection as far back as 2012. Those states include California, South Carolina and, until recently, Louisiana.

“Walmart’s recent win in the Louisiana Supreme Court further highlights how important it is for state and local jurisdictions to set up clear guidance for market facilitator laws, instead of looking back and trying to collect pre-Wayfair taxes,” wrote Vertex chief tax officer Michael Bernard in a recent blog post,

A few states have post-Wayfair legislation underway as well, including Alabama, Colorado, Kansas, Louisiana and Texas, according to the Tax Foundation.