Mayor Byron W. Brown is relying on the city’s surplus funds and many unfilled positions to keep his pledge not to raise taxes.

The mayor’s proposed budget for 2013-14 calls for the use of $12 million in unrestricted surplus funds and expects that the city will employ 50 fewer people as workers retire and positions are left open.

Brown unveiled a $482.5 million spending plan Wednesday for the year that begins July 1. The proposal calls for $100,000 less spending than in the current budget. It would keep property taxes for residences level and reduce taxes for commercial properties by 3.2 percent.

No fees would increase, and the city’s rainy day fund – enough to cover all expenses for a month – would remain intact, Brown said. The city’s unrestricted fund balance also would grow, but Brown did not say how.

“We feel this is very prudent budgeting,” he said. “The fund balance at the end of the day will be substantially the same as it was going into this budget year.”

The city’s credit ratings are the highest in its history, but ratings agencies have shown concern that continued use of funds left over from prior years to cover recurring expenses could affect the city’s long-term fiscal health.

Since Brown took office, residential property taxes have decreased by 15 percent, and commercial property taxes have decreased by nearly 28 percent.

The Buffalo News asked the Brown administration several follow-up questions about the budget, but they were not answered.

They include:

• How did the city’s unrestricted surplus, which can be used for any purpose, increase by $11 million? The city’s audited financial statements, released at the end of 2012, stated that the unrestricted surplus was $12.2 million, but Brown said Wednesday that it was $23 million.

Funds that had been restricted were now free to be spent, Brown said, but he did not elaborate.

• How does the budget supplement the loss of $18.7 million in state aid the city had in 2012-13 but will not have in 2013-14?

Common Council President Richard A. Fontana said that he was happy the commercial property rate would be going down but that he was concerned about the proposed budget’s use of fund balance. The Council, which begins budget hearings today, has until May 22 to amend the spending plan.

Budget highlights include:

• $70.3 million to fund the school district, which is the same as it has been in prior years.

• The highest allocation for summer youth employment in the city’s history. The city would spend $1.1 million, employing about 1,400 young people.

• $1 million for police cars, covering the purchase of 25 to 30 vehicles.

• $171,000 to fund two attendance teachers in the city school district.

• The city plans to demolish nearly 325 blighted structures, using $6.5 million from various sources, including $500,000 from the proposed budget.

• A new competitive grant of $100,000 for cultural organizations. Many arts and cultural groups are still waiting for funding from the current budget year, which is expected to be distributed in the next few weeks, Brown said.

• Funding for new classes of police officers and firefighters. The number in each class was not available Wednesday.