Among its many challenges as the City of Detroit continues to dig its way out of ifs difficulties has been its inability to enforce tax collection. For instance:

"About 6 percent of U.S. taxpayers break the law by not filing with the Internal Revenue Service each year, according to research by economic consultant Brian Erard. In Detroit, [it is] estimated, 46 percent of taxpayers hadn’t submitted their 2014 returns by the due date in the following year."

This led to an interesting experiment to see what works best to improve this.
The city decided to send out more than 7,000 mailings to deadbeat tax filers, people whose 2014 tax returns were already a year late. The city suspected each delinquent owed at least $350. Taxpayers were randomly selected to receive one of six different letters, each with a different message in a black box on the mailing.

One message appealed to residents’ civic pride, as the city tried to bounce back from its bankruptcy: “Detroit’s rising is at hand. The collection of taxes is essential to our success.”

Another simply made clear that the city’s tax collectors had detailed information on the deadbeats: “Our records indicate you had a federal income of $X for tax year 2014.” Detroit residents owe 2.4 percent of their incomes to the city, after a $600 exemption. Nonresidents who work in Detroit pay a rate of 1.2 percent.

And one message made a bold declaration: “Failure to file a tax return is a misdemeanor punishable by a fine of $500 and 90 days in jail.”

It turned out that the threat worked best. More than 10 percent of taxpayers responded to the letter mentioning a fine and jail time, more than three times the response rate of a basic control letter.
And for those who may be "bunking" in Detroit [living in Detroit but claiming residency outside], watch out.

Officials noticed that only one in five residents in several high-end apartments buildings had filed income taxes. The city persuaded a judge to issue an order requiring landlords to turn over tenant information.
http://www.crainsdetroit.com/article...s-that-threats