The aftershocks of events at the federal level continued to have major tax repercussions at the state level throughout 2019.

As was the case last year, the annual list of the top developments in the state tax arena compiled by Jamie Yesnowitz, principal and SALT practice and National Tax Office leader at Top Five Firm Grant Thornton, is dominated by two issues: the Tax Cuts and Jobs Act, which was enacted at the end of 2017, and the Supreme Court decision in South Dakota v. Wayfair, Inc. which was decided six months later in June 2018..

In fact, “The top two spots, and four of the top seven spots deal with the states response to Wayfair,” Yesnowitz said. “The states’ and localities’ overwhelming reactions to Wayfair through sales tax and income tax nexus changes and the expansion of sales tax responsibilities to marketplace facilitators are impacting all businesses in a significant way. On the sales tax side, remote sellers and online marketplace operators face a brave new world with expanded compliance, and the need to collect the correct tax amount — not too much,and certainly not too little.”

Here are Yesnowitz’s top SALT stories of the year, listed this year, for the first time, in order of importance: