The city of Boston has sent letters to the 40 largest local nonprofit organizations asking them to make regular payments for municipal services, writes The Boston Globe.

The city requested up to 25 percent of what the hospitals, universities, and cultural institutions would pay if they were not exempt from taxes.

“We’re looking for fairness for Boston taxpayers and the nonprofits,’’ said Thomas M. Menino, Boston’s mayor. “This isn’t something we drew up on the back of an envelope. It’s something we put a lot of thought into.’’

The coordinated effort, thought to be the first in the nation, is based on estimates of what it costs to provide the organizations with city services, such as police and fire protection.

The formula is designed to increase payments gradually over five years, from the $15-million that major nonprofits paid in 2011 to $48-million.

With property assessments for the 40 groups valued at a total of $13.6-billion–or more than half the total for all commercial property in the city, the organizations would pay $404-million if they were not tax-exempt, according to the city’s Assessing Department.

Although many Boston groups have long made voluntary payments for such services, support for the new plan is mixed, says The Globe.

“We have some boards of trustees that are asking, ‘What are the implications? Does this exist elsewhere in the country? Are there precedents we need to be considering? Are we heading down a slippery slope?’ ’’ said Richard J. Doherty, head of the Association of Independent Colleges and Universities in Massachusetts.