HOULTON, Maine — Residents are once again seeing an increase in their property tax bills as school budget and fuel increases and a lack of available surplus funds have prompted a spike in the mill rate.

Interim Town Manager Cathy O’Leary said Monday that tax bills mailed out last week reflect the current mill rate of $19.95 per $1,000 of valuation.

That’s a $1 increase from the tax rate of $18.95 set in July 2011.

O’Leary said a number of factors contributed to the jump, including a spike in the SAD 29 school budget, an increase in the Aroostook County tax, and higher expenses for fuel and other items.

In the past, the town has dipped into its surplus fund to offset taxation and hold or lower the tax rate, but the council refrained from such action for the second straight year.

“We have not built the fund up enough,” O’Leary said Monday afternoon.

Town Treasurer Nedra Hanson said the undesignated fund balance stands at $471,880, which is up more than $200,000 from the prior year.

Still, the account balance is much smaller than it has been in current years, when it contained more than $1.2 million.

The town is trying to build the surplus account back up to an acceptable level before spending any more of it. The town’s auditor has recommended that the surplus account contain at least $1 million.

The town’s tax rate hovered at 18.5 mills for two years until it decreased to 18.25 mills in 2007. The rate remained steady before it increased by 1 mill in 2009. The figure has crept up slowly ever since.

Each year, the council dipped into its surplus account to hold or decrease the mill rate. That began to change in 2010, when a number of factors influenced the decrease in the surplus account. They included lower than expected ambulance revenues and a nearly $300,000 dip in state revenues.