Mayor Bloomberg’s announcement last week of his decision to consolidate the Department of Correction with the Department of Probation under the commissionership of Martin Horn said the merger would “create greater efficiencies by reducing administrative costs” and “eliminate redundant functions.”

Well, now that the mayor has gotten started on this worthwhile path, he might want to have a look at the rest of the city government. One of the reasons the city is facing a $6 billion budget gap, and that its residents pay some of the highest taxes in the country, is that we’re getting double-billed by multiple city agencies with similar functions.

How many other cities, after all, can boast both a “Department of Information Technology and Telecommunications” and a separate, independent, “Department of Records and Information Services”? If the information technology department can’t handle the information services tasks, how about moving some of the municipal archives functions over to the New York Public Library, and some of the matters involving birth and death certificates to the Department of Health? And while we’re at it, why don’t phones and computers qualify as “administrative services” and fall into the Department of Citywide Administrative Services?

Or take, for instance, the city’s Department of Housing Preservation and Development, which, according to the Mayor’s Management Report, seeks to “increase the supply of affordable housing,” presumably to cut down on homelessness in the city. So why does New York also have a Depart ment of Homeless Services? Its job is to provide emergency shelter and other services to the homeless, as well as trying to get them on the right track toward being self-sufficient. Are these two missions so separate as to require separate departments, each with its own staff, supplies, office space, vehicles, and other expenses? The city spends about $62 million on the Department of Housing Preservation each year, on top of the nearly $300 million it spends on the Department of Homeless Services.

The Department of City Planning says that its goal is to “promote orderly growth, improvement, and future development of the city.” The Landmarks Preservation Commission, on the other hand, is set up to “optimize and preserve the city’s architectural, historical, cultural, and archeological assets.” Both deal with plans and development. Are these tasks so different as to require two separate agencies?

The New York City Taxi and Limousine Commission, which monitors the city’s taxi medallions and licenses, spends $4.5 million per year on administrative costs, $2 million on rent alone. The Department of Transportation, meanwhile, has 4,500 employees whose mission is to administer to the city’s roadways and highways. Are the taxis not an integral part of the city’s transportation system? Merging these two offices would save millions in administrative costs.

Likewise, though the Human Resources Administration spends part of its $5.8 billion budget on its Office of Employment Services, the city still has a separate Department of Employment. The Department of Employment manages the Summer Youth Employment Program, the “Out-of-School Youth Program” and the “In-School Youth Program.” Why, then, is there a need for a separate “Department of Youth and Community Development”?

A spokesperson for the city’s Independent Budget Office, Doug Turetsky, said consolidation would give the city “an opportunity to get rid of some duplication.” Mr. Turetsky told us that there are dozens of offices throughout the city that could be eliminated if the city was really interested in cutting down on bureaucratic overlap. With the city’s hiring freeze, Mr. Turetsky said, there just may be an opportunity for some actual staffing reductions to make these consolidations result in meaningful savings.

Following the mayor’s appointment of Mr. Horn, council speaker Gifford Miller’s office sent out a press release saying that while the merger of Correction and Probation “at first glance … seems to meet the City Council’s calls for consolidation of city agencies,” that “the devil is in the details.” The devil, indeed. Those of us who live outside the strange logic of city government might be more inclined to think the devil is in the taxes and fees New York’s overtaxed citizens have to pay in order to have the same job done multiple times. Just the consolidations mentioned here, by our estimate, would provide another $25 million toward closing the budget gap.