NASHVILLE — State agencies have until Dec. 30 to submit two-tiered plans detailing how they will cut an average of 14.58 percent from their base budgets in the upcoming 2009-2010 budget, according to a memo issued Tuesday by Finance Commissioner Dave Goetz.

Department heads and the budget office also have been ordered to prepare for possible 5 percent cuts on top of that. That would bring most departments’ base budget reductions to nearly 20 percent “if economic conditions continue to deteriorate,” Commissioner Goetz’s memo says.

Officials had little immediate comment on the memo, issued late Thursday afternoon.

Gov. Phil Bredesen and administration officials have warned in recent weeks that cuts of up to 20 percent are possible at state agencies as Tennessee grapples with revenue shortfalls resulting from what some economists say could be the worst economic downturn since the Great Depression.

But Commissioner Goetz’s memo, the result of huddled behind-the-scenes deliberations by the governor and top officials after public budget hearings several weeks ago, contains the first concrete numbers and instructions.

“You should develop base reduction plans with the assumption that implementation of the reductions will be necessary to balance the budget,” Commissioner Goetz warned in the memo.

The document throws out one glimmer of hope, saying if revenues stop their downward slide and Congress in January passes a major economic stimulus package providing $400 million in “fiscal relief or federal revenue sharing” to Tennessee, cuts “potentially” could fall to about 8.28 percent.

Goetz spokeswoman Lola Potter said the $400 million in federal relief referred to in the document “is a conservative estimate as to what could come to the state in federal stimulus.”

The State Funding Board is projecting a revenue shortfall in the current 2008-2009 fiscal year of between $884.6 million and $1.023 billion. With revenue projected to grow only between 0.25 percent to 2 percent in the 2009-2010 budget that will begin July 1, the state’s revenue base will be lowered to between $712.1 million and $1.001 billion.

According to the Goetz memo, most state agencies that depend on general fund revenues will submit cuts of 14.76 percent, with the average being 14.58 percent. Higher education is being directed to cut 14.58 percent, the memo states.

The cuts will be presented in two tiers. Tier 1 will be set at 7.74 percent for most agencies and 8.28 percent for higher education. Tier 2 would bring the cuts up to the 14.58 percent average for state agencies and higher education. Most state agencies would see 14.76 percent reductions.

Gov. Bredesen previously has said he anticipates cutting roughly $150 million from higher education’s estimated $1.2 billion in funding. Efforts Tuesday evening to contact Senate Education Committee Chairman Jamie Woodson, R-Knoxville, were unsuccessful.

Commissioner Goetz’s memo says the Education Department would be cut $70 million with $40 million of that coming in Tier 1 reductions. But the memo re-emphasizes Gov. Bredesen’s publicly stated priorities that cuts not affect the Basic Education Program funding formula for schools and the governor’s pre-kindergarten initiative. Also spared are career ladder salary supplements and several Bredesen initiatives such as the Books from Birth program.