As if New Yorkers didn’t already suspect that they’re far more heavily taxed than residents of other big cities, the city Independent Budget Office yesterday issued a study proving it more conclusively than ever.

The IBO said New York’s state and local “tax effort” in fiscal 2003-04 was $9.02 per $100 of taxable resources produced by city households and businesses. For the eight next-largest U.S. cities, the average came to just $6.16.

Building on an IBO analysis first issued in 2000, the new study is special in two ways: It considers both state and municipal tax burdens, and it details the extent to which these taxes are pushed up by New York’s generous social services – especially Medicaid. At nearly triple the per-capita average for the other cities, Medicaid and public assistance accounted for roughly half of the added tax burden in New York, the IBO found.

One thing the IBO didn’t do is provide more ammunition for city officials who like to blame high taxes on Albany and demand the state pick up more costs.

As the study shows:

If the state government took complete responsibility for Medicaid and public assistance, New York City’s combined tax effort would drop only slightly – to $8.51 per $100, or still 38 percent above the average for the other large cities.

Even with Medicaid and public assistance completely removed from the calculation, New York City’s state and local tax burden would be 25 percent above the big-city average.

But nonetheless, the study highlights the importance of Gov. Spitzer’s looming budget battle with the health-care lobby because, rather than shifting more costs to the state, he wants to trim overall program spending – which would be a plus for city and state taxpayers alike.

No matter who picks up the nonfederal share of the tab, New York’s wildly out-of-line Medicaid costs are a significant obstacle to making the city more competitive.