ROME — Despite the government’s best efforts, tax evasion remains something of a pastime in Italy, where, famously, more than a few of the Ferrari-driving set claim impoverishment when it comes to declaring their incomes.

So this month, not without controversy, the National Revenue Agency decided to try a new tack. Rather than attempting to ferret out how much suspected tax cheats earn, the agency began trying to infer it from how much they spend.

The new tool, known as the “redditometro,” or income measurer, aims to minimize the wiggle room for evasion by examining a taxpayer’s expenditures in dozens of categories, like household costs, car ownership, vacations, gym subscriptions, cellphone usage and clothing. If the taxpayer’s spending appears to be more than 20 percent greater than the income he or she has declared, the agency will ask for an explanation.

In a country that is desperate for revenue to straighten out its ailing public finances — and where newspapers routinely publish articles about Lamborghini-loving proletarians — one might expect the redditometro to attract some support, at least among Italians who file truthful tax returns. Yet the redditometro has run into strong opposition, not least from the nation’s suffering retailers, who are worried that it will discourage consumer spending and sink their businesses further. Others have criticized it on civil rights grounds, saying it is overly intrusive.