The migrant crisis facing Massachusetts and putting a serious strain on its budget will get dramatically worse in the years to come if lawmakers don’t do something to address the problem now, according to a new report from the Center for Immigration Studies.

According to the case study, there are 355,000 “illegal and inadmissible migrants” living in the Bay State, 50,000 of whom arrived over the last three years. Many recent arrivals, study authors claim, are in the country under a federal “parole” program and may already be eligible for state provided services, and many more could become eligible in the coming years.

“A significant share of migrants settling in Massachusetts who entered under Biden parole programs, including Ukrainians, Haitians, and children, may be eligible for welfare programs upon arrival,” study authors write. “Other parolees may become eligible for welfare programs five years after entry, regardless of whether they ever attain legal status. This cohort represents a potential fiscal time bomb in terms of welfare costs, beginning in 2026. The additional annual cost for SNAP benefits alone just for the parolees in Massachusetts could be $4.6 million.”

Massachusetts is coming up on one year since Gov. Maura Healey declared that a state of emergency existed in the commonwealth as a result of the influx of migrants. The governor followed her declaration with new rules for the state’s Emergency Assistance shelter system, capping the number of families that might be housed by the state at 7,500. The cap was reached not long after.

According to Healey, the migrant crisis is not one the state can address alone while immigration and border patrol are entirely the purview of federal authorities, some of whom have demonstrated they possess no real urgency to solve the long-standing problem.

State budget writers, in planning for another year of filled-to-capacity shelters, set aside $1 billion to pay for migrant housing and other services. According to Jessica Vaughan, director of policy studies at the Center, those costs will only go up.

“A massive wave of generous taxpayer-funded welfare benefits will go into effect for illegal and inadmissible migrants unless action is taken. Some of this is due to federal policy failures, but it is significantly exacerbated by the policy choices of Governor Maura Healey and State House leaders to extend the social safety net to illegal migrants. The cost of these choices inevitably reduces the state’s ability to provide for American citizens and legal immigrants who need assistance,” Vaughan said.

“It simply is not sustainable to have a generous welfare state with mass illegal migration,” she said.

Republican state Sen. Ryan Fattman, of Sutton, said the report released Thursday demonstrates that the time to act toward a fix for the shelter system is now, before the tab grows too large to close.

“Our caucus has time and again proposed common-sense reforms designed to both reduce the pull factors bringing migrants from the southern border all the way to Massachusetts and to ensure that both our state and local governments do not become overwhelmed. This study demonstrates plainly that the long-term impact on Massachusetts finances will be devastating. This problem is only going to continue to get worse. The time is now to reform our state’s broken right to shelter law,” Fattman said.

“This isn’t about people, it’s about policy, and the policies that the commonwealth has adopted are truly generous and unsustainable,” he said.

State Rep. Marcus Vaugn said some of his constituents are bearing the brunt of the burden brought upon state residents by the policies of the Healey Administration, which has sent hundreds of migrant families into several small towns.

“Small bedroom communities like mine are being required to shoulder the very high economic cost for the state’s broken policies. A small town like Norfolk, which has about 11,000 residents, has suddenly seen hundreds of migrants enter the community, and is being required to provide the social services, schools, and other accommodations necessary. This is unsustainable for the state and for small suburban towns like the towns I represent,” the Wrentham lawmaker said.

The Massachusetts Fiscal Alliance said the migrant problem facing the Bay State is the direct result of choices made by lawmakers on Beacon Hill.

“Massachusetts taxpayers better be ready for the fiscal time bomb our Governor and State House leaders have set us up for,” MFA spokesman Paul Craney said.

A spokesperson for the Healey Administration said they could not verify or refute the numbers offered by the study authors — which are “estimates based on a variety of government and news sources” according to the study — but did push back on some of the other assertions offered by the Center.

The state’s extension of SNAP benefits to migrant families late last year, which study authors say was “quietly passed” as part of a supplemental spending bill, was designed so that only lawfully-present migrants can qualify, the governor’s office said, and families with no documentation or who are not federally recognized are not eligible for state provided shelter.

Massachusetts stands alone among the 50 U.S. states in guaranteeing a right to shelter for families with small children and expecting mothers.