ALBANY — As the budget process for the next fiscal year begins, Gov. David A. Paterson continues to clamp down on state spending.

On Friday, the governor ordered state agencies to "keep their spending flat" when preparing their budget requests for the 2009-10 fiscal year.

"To achieve this zero growth target, you must prepare a budget submission that fundamentally reevaluates whether to continue funding for many lower-priority programs unrelated to your core mission," the governor wrote in a memorandum to agency heads. "Unlike in the past, we must focus our efforts on controlling state spending and assess whether certain initiatives should be eliminated or experience real, year-to-year reductions."

In the memo, Gov. Paterson pointed out two problems he wants to pull the plug on. One is that once a program is added to the budget, it becomes "extremely difficult" to eliminate it, regardless of its effectiveness or importance. The other is the idea that slowing the rate of increase of a program's funding amounts to a cut.

"Our current fiscal difficulties present an opportunity to break New York's cycle of increasingly unaffordable budgets," the governor continued. "I have already requested that you create an inventory of all your programs and rank them in relation to your core mission. Now, I am asking that you put forward a budget request that keeps your agency's spending flat compared to 2008-09 levels."

"Given the substantial deficit we are facing, additional reductions may be necessary," he wrote. "But your initial proposals will help begin a serious dialogue about how best to control state spending in next year's budget."

Since taking office March 17, the governor twice has directed state agencies to reduce their budgets, first by 3.35 percent in March and then by an additional 7 percent in July. These cuts resulted in savings of $1.1 billion in the current budget, he said.

Last month, Gov. Paterson called the state Legislature back into a "special economic session" that resulted in $1 billion in further cuts spread over the current and next fiscal years.

Accompanying the governor's memo was a "call letter" from state Budget Director Laura Anglin to agency leaders, formally beginning the budget process for the 2009-10 fiscal year.

"I understand that preparing a zero growth agency budget proposal will be difficult," she wrote. "It will require that you advance creative proposals for reducing costs, streamlining your operations, and increasing productivity. To the extent possible, you should examine options for consolidating services, coordinating programs with other agencies, and eliminating outdated or costly statutes and regulations. Capital requests should be limited to those that are essential to health and safety."

Ms. Anglin directed agency heads and commissioners to submit their budget requests to the state Division of the Budget by Oct. 3.

The projected deficit for the 2009-10 budget is $5.4 billion; it is forecast at $24.4 billion over the next three fiscal years.

"We cannot continue making excuses for why the state is unwilling to limit its expenses at a time when hard-working taxpayers are forced to do the same thing every day," Gov. Paterson wrote. "Change is never easy. But it is unavoidable if we want to stem the tide of unsustainable spending growth, job losses and declining population that has plagued New York for decades. And this is a task we must begin immediately."