Congress and the White House can make a sound case for tightening up eligibility requirements for Medicaid enrollment, but that doesn’t excuse doing it at state expense – or leaving states in the dark about many important details, even on the eve of implementation.

As of Saturday, needy people who apply for Medicaid benefits will have to prove their U.S. citizenship, preferably by providing a birth certificate, naturalization papers or passport. The idea is to filter out illegal immigrants who, by law, are ineligible for Medicaid, the state-federal program that covers health-care costs for the low-income.

The Congressional Budget Office has estimated the move will save the country $735 million over the next decade, Stateline.org reports. But the transition is complicated and unclear, and it exacts a price in terms of anxiety for the poor and significant funds for the states.

State officials are assuring current Medicaid recipients that they will have a reasonable time in which to satisfy the law – the million current recipients in Washington state won’t just be pitched off the rolls. It isn’t as clear what awaits the 55,000 new applicants the state sees every month.

Only in the past couple of weeks has the U.S. Department of Health and Human Services sent the states a list of methods, ranked by reliability, that are acceptable for establishing citizenship. Passports and naturalization papers are at the top, affidavits from witnesses at the bottom. But the feds intend to audit state compliance, and they want to see heavy use of the high-reliability options. Regardless of the methods employed to establish citizenship, the new requirements will inundate state workers with paperwork and require new caseworkers to handle the load.

Gov. Chris Gregoire estimates it will cost Washington state an added $5 million a year to help the federal government save money.

On top of everything else, the list of documentation categories is just a list. It’s not the official rule that state officials still are waiting for, four days before the law takes effect.

Normally, the federal government gives local and state agencies months of advance warning about new regulations. What went wrong this time is unclear, but carrying such confusion and uncertainty down to the wire is unfair, not only to the beneficiaries whose lives are impacted but also to the agencies who will have to put people and systems in place with appallingly inadequate notice.