For two years, Loudoun County School Superintendent Edgar B. Hatrick III has proposed annual budget plans that account for what he says are the basic needs of a rapidly growing public school system. And for two years, Hatrick has watched the School Board and the county Board of Supervisors cut those spending proposals by millions of dollars.

With the arrival of what promises to be yet another challenging budget cycle, Hatrick has said that the spending plan for the 2014-15 school year will again highlight what will be needed to keep pace with the county’s growth and maintain the school system’s reputation. But this year — Hatrick’s last as superintendent, a position he has had for more than 20 years — he also cautioned that the budget will reflect the cumulative costs of cuts and deferrals made during previous years.

Hatrick, who announced in June that he will retire after the current school year, is scheduled to present the budget before the School Board on Tuesday. Last month, he wrote an open letter about the fiscal 2015 plan, urging the School Board and county leaders to have an “honest, productive” conversation about the future of Loudoun’s educational system, which he said has reached “a tipping point.”

Many of the budget cuts in recent years have come from deferrals and delays, Hatrick told The Washington Post in an interview, but those temporary fixes ultimately increase the budget deficit. He said he wrote the open letter because this budget will be the last one he presents to the School Board and he thought it was his responsibility to be clear about the state of the school system’s needs before leaving his position.

“I do not believe it is fair to the next superintendent to have that person be responsible for proposing a budget that addresses these accumulating needs,” he said. “Although we have appeared to ‘make it work,’ the truth is that in areas such as salaries, we have simply put off, and the result is an ever-growing financial problem to solve. . . . These growing deficits occurred under my watch, and it is my responsibility to put them before the public before I retire.”

Last year, the School Board cut nearly $17 million from Hatrick’s proposed budget before sending the plan before the county supervisors for review. Even with the cuts, the School Board’s adopted budget marked a $36 million increase over the school system’s previous fiscal plan.

It was the second consecutive year that School Board members, many of whom had pledged to reduce spending during their 2011 election campaigns, made cuts to the budget before it was presented to the Board of Supervisors. In 2012, the School Board trimmed Hatrick’s proposal by more than $12 million. Employee benefit plans were re-formatted, new positions were eliminated, and technology improvements and other programs were scaled back, among other reductions.

The cuts came in response to pressure from the supervisors, who had made it clear that the school system, which accounts for more than $840 million of the county’s $1.8 billion fiscal 2014 budget, was expected to reduce its costs. The all-Republican board has made lowering tax rates a priority during annual budget discussions.

In March, as supervisors prepared to adopt a county budget that would leave the school system facing a shortfall of more than $15 million, Chairman Scott K. York (R-At Large) voiced frustration about the school system’s spending and declared from the county dais that it was time for change “at the top,” a clear message to Hatrick.

Nearly a year later, the superintendent has penned an equally clear response.

“No county in Virginia has ever grown at the rate of Loudoun for a sustained period and maintained the low real-estate tax rate that we have enjoyed,” he wrote in the open letter. “Look to the history of Fairfax and Prince William for case studies of the effects of residential development in creating growing demands for services. Both counties lived through many years of tax rates of $1.50 or more, something Loudoun has never experienced.”

As Loudoun’s spending per student has dropped to a little more than $11,500 — down from nearly $13,000 in 2009 — the results have been clear, Hatrick said. Classes are getting bigger, demands on faculty are mounting and salaries are no longer as competitive with those of other school systems in Northern Virginia, making it difficult to attract and retain talented educators.

“Critical technological infrastructure and county and school employees have borne the brunt of budget decisions that focused primarily on tax rate,” Hatrick wrote. “More importantly, our young people, who are our future, have borne the real burden in larger classes and threatened diminishments of the opportunities available to them in our schools and in our community — all in the wealthiest county in America.”

Student growth has slowed in recent years, but about 2,300 new students are added each year, according to schools officials. Hatrick said the school system’s projected operating budget by the year 2019 will exceed $1 billion.

In an e-mail, Hatrick said his upcoming budget proposal does not contain new initiatives but is instead focused on existing programs that have not been adequately funded. He said he hopes the School Board will not feel pressured by county supervisors to make deeper cuts again this year.

“Their role is to advocate for the needs of the school system and to work with the Board of Supervisors to obtain the funding that is needed for that school system,” Hatrick said of the School Board, “not to work toward a pre-decided tax rate.”