Michael B. Campbell, president of the Baltimore fire officers union, said several of his members have lost coverage for their children. One member told Campbell he sent in forms, but the city dropped his dependents anyway.

"I think these people fell through the cracks," he said. "I guess you've got to take your family and wrap them in bubble wrap until January."

Rawlings-Blake has been targeting health care expenses as one of several ways to cut a projected $750 million long-term budget deficit. She has said that nearly half of Baltimore's municipal employees and retirees have a "critical or chronic" illness — a distinction that contributes to the high cost of providing their health insurance.

The city has modified health benefits to charge lower premiums but require higher co-payments. That move will save the city more than $20 million a year, on top of $6.5 million saved through dropping ineligible dependents, officials said.

Tazelaar described the move as a groundbreaking way to save money, part of a 10-year plan to improve city finances.

"This is the first time a health care audit has ever been done for the city for dependents," he said.

Tazelaar said city officials believe some of the workers did not respond because they knew they had someone other than a spouse, domestic partner, child or legal dependent enrolled in the city's health care system.

"Of course, some people didn't respond because they knew they didn't have the documentation to prove their dependent was legal," he said.

Baltimore paid $15,732 last year to provide health benefits for a typical city employee — according to the city budget — and more than $250 million for employees and retirees.

But Clarke and Middleton said the city made life difficult for workers in its effort to cut costs. The city required marriage licenses, birth certificates and bills as ways of proving the identity of dependents.

Clarke said she and her husband had lost their marriage license from decades ago. "My dear husband went all the way back to the church where we got married, and by some miracle, they still had it," she said. "I know the trouble we and others went through to comply."

The unions say they're urging officials to reconsider. Campbell said he hopes the city will allow appeals by city workers — even those who did not submit a form.

"This is a mess," Campbell said. "It should be corrected."