THE CITY OF BOSTON filed an amicus brief Thursday on behalf of 34 cities, counties, and municipal agencies asking a federal court to stop a new rule from going into effect that would nearly double the cost to apply for citizenship.

Beginning October 2, the US Citizenship and Immigration Services (USCIS) is increasing its fee to apply for naturalization from $725 to $1,200 — and eliminating the fee waiver for almost all low-income residents. The agency is also increasing the application fee for people seeking green cards and creating a first-time application fee for those requesting asylum.

 Project Citizenship, a New England nonprofit that helps green card holders to complete their citizenship application, sued the Department of Homeland Security and USCIS in US District Court on August 17, claiming the plan discriminates against low-income immigrants. The organization is seeking an immediate injunction that bars the federal government from upping the cost of applying.

The city and its co-signatories support a move for a preliminary injunction that would stop the federal government’s effort in its tracks.

“The wealth test created by the challenged rule will have a chilling effect on naturalization rates in the amici’s communities as well as across the country,” write the authors of the brief. “This will have a profoundly negative effect on municipalities and their immigrant populations.”

The amicus brief highlights how local governments have invested in supporting the naturalization process, how naturalized citizens benefit from the support, and how naturalization increases the civic and economic health and resilience of local communities for all residents.

The Department of Homeland Security says it is adjusting many USCIS fees to help recover its operational costs. “Current fees would leave the agency underfunded by about $1 billion per year,” read a July press release.

“These overdue adjustments in fees are necessary to efficiently and fairly administer our nation’s lawful immigration system, secure the homeland, and protect Americans,” said Joseph Edlow, USCIS deputy director for policy, in the July release.

 The agency said the last time it updated its fee structure was in December 2016.

Advocates and elected officials say the fee increases send the wrong message. “These fee increases go against the values America was founded on,” said Boston Mayor Marty Walsh in an email. “People come to the US for a better life for themselves and their families, whether that’s 400 years ago or yesterday. This new rule creates a wealth test to be an American, and citizenship must not be reserved for those who can afford it.”

Currently, immigrants who have an income that is less than 150 percent of the federal poverty level qualify for a full fee waiver, and those with an income between 150 and 200 percent of the federal guideline qualify for a partial fee reduction. Those waivers would be eliminated under the new rule.

Cities as wide-ranging as Albuquerque, New Mexico; Austin, Texas; Boise, Idaho; Minneapolis, and Cambridge have signed on to the brief, along with many others.

There are about 9 million people in the US eligible for citizenship, more than 30,000 of them in Boston. The Boston announcement comes on Constitution Day, when the city partners with Project Citizenship to host the largest annual citizenship workshop in New England, when more than 400 community volunteers, law students, and pro bono attorneys help hundreds of people with their citizenship application for free.

To date, the city has helped 1,815 people become citizens, and last year  59 percent of applicants qualified for the low-income fee waiver. Project Citizenship assisted 1,974 legal permanent residents in filing for naturalization in 2019.