In what he terms an “unintentional over-expenditure,” Suffolk treasurer Ron Williams exceeded the total budget appropriation for his office in fiscal year 2010 by more than $9,000.

Williams says the error occurred because he provided a salary supplement to an employee who is doing two jobs because one of the most critical positions in the office was frozen.

“This situation occurred as a result of the Chief Deputy Treasurer for Accounting position being frozen, and the need to supplement the staff member acting in that position, in conjunction with the sweep of turnover vacancy dollars from the open position,” Williams wrote in a letter to City Council.

The position has been vacant since October 2008, when the person formerly in the job moved out the area.

“I was working with [human resources] in an effort to fill the position,” Williams said. “I just did not have a pool of qualified applicants I was satisfied with at that point.”

Soon, City Manager Selena Cuffee-Glenn froze the vacant position as part of cost-cutting measures.

“It was deemed by the city manager to be a non-essential position, so it was frozen,” Williams said. “I challenged that but was not able to prevent it.”

Virginia Carr then took over many of the job’s responsibilities, Williams said. The human resources department then came to him about providing Carr extra money.

“I didn’t request this supplement,” Williams said. “HR came to me and said that city policy calls for someone who’s acting in a position be paid at the minimum [of the higher position].”

Carr’s base salary, $44,318, was then supplemented by $9,406 to bring her to a total pay of $53,724. In the fiscal year 2010 budget, funding for the vacant position — more than $60,000 — was eliminated entirely. An adjustment was never made in the budget, which caused a $9,117.65 shortfall, subsequently caught by auditors doing a customary review of the city’s books.

Carr still is receiving the supplement, which means the treasurer’s budget is again in danger of falling short.

Williams has asked the city manager to reduce his current fiscal year budget by $18,236 to correct last year’s overspending and this year’s potential for overspending. He pledged to scrimp on office supplies and other expenditures to make up the difference.

He also told council members in an email that plans are being developed by the finance director to avoid similar events in the future.