Fairfax City Treasurer Frances L. Cox is bracing for one of the toughest campaigns in her 27 years as the head of the city treasury.

Her two opponents on the Nov. 3 ballot have stocked an arsenal of city audit reports critical of the operation of her office. Ray M. Birch and Terry E. Ingalsbe have been marching door-to-door for weeks, armed with excerpts from those audits, alleging Cox's operation is inefficient and inadequate.

And Cox has returned the fire, blasting her opponents with denouncements and denials.

She charges that 27-year-old Ingalsbe is "too immature" for the job and that Birch, 56, "had his own problems with the auditors" when he was assistant director of the Fairfax County office of finances.

Cox calls it a "nightmarish campaign." She claims her opponents have been dishing out misleading information, citing figures out of context.

"The audits are short and to the point," Ingalsbe fires back. "It's hard to take them out of context."

It is not the first time Cox, 56, has traded political barbs with Birch or Ingalsbe. Birch ran unsuccessfully against Cox for the treasurer's post four years ago. Ingalsbe worked for Cox for two years as assistant treasurer. He left on stormy terms three years ago.

Audits of Cox's office over the past several years have cited examples of poor accounting procedures and inefficient methods of handling the city's money. Each year the audit says Cox has improved one area of the operation but points out new problems. City auditors have cited Cox several times for costly delays in depositing large incoming checks.

"They're talking about technicalities," Cox counters. "Auditors don't come to praise, they come to make suggestions for improvements."

But Ingalsbe and Birch argue that since the same complaints are filed year after year, Cox is not following up on those suggestions.

"Her response is that she is now reorganizing her office," Ingalsbe says. "That's the same thing she says at the end of every report."

"The improvements the auditors keep requesting never seem to get implemented," Birch adds.

The 1981 audit report presented to the City Council Tuesday night was almost a carbon copy of last year's audit. The auditors said the treasurer's daily cash report "is often several weeks overdue" and often shows discrepancies between the cash report and the actual deposits.

The treasurer's system of recording checks received for personal property and real estate taxes is inefficient and could "result in lost revenue to the city," according to the auditors.

"There's no question there are time delays" between the deposits and the cash reports, admits Cox. She said she favors changing the accounting system to cut down on time lags in the current process. But Cox also notes that many of the problems in her office are caused by the city's small computer processing system -- a system over which Cox says she has no control.

Cox said she thinks city officials were "playing politics" by presenting the auditor's report in a public council meeting barely three weeks before the election. The report has been presented to the council during October for the past several years, however.

Ingalsbe is preparing a second round of mailings highlighting what he views as the deficiences of Cox's office. He said his two years working under Cox gave him a first-hand look at the problems in her operation.

Birch is running on his 29 years of service in the Fairfax County financial office.

This is not the first time Cox has come under heavy fire. Although no one has accused her of wrongdoing, city officials have criticized her repeatedly for what they term the poor operation of her office.

Cox argues that most of the attacks against her have been politically motivated.

She notes she is "four years short of retirement," but she refuses to say whether this will be her last bout at the ballot box.

The heated race for the job that pays Cox $41,200 a year has stolen most of the limelight from the city's other campaign, the two-candidate contest for commissioner of revenue.

John L. "Jack" Reed Jr., 57, advertising director for a local monthly newspaper, and Juanita W. Dickerson, 49, a tax technician in the city revenue office, are seeking the job now held by A. Howell Thomas. Thomas is retiring from the position at the end of his current term.

As to issues in the campaign, Reed says, "I don't see any."

Both candidates say they spend most of their time on the campaign trail explaining the difference between the duties of the commissioner of revenue and the treasurer: commissioner of revenue does the billing, the treasurer does the collecting.

Reed says he has been active in city, congressional and presidential elections, but this is his first attempt at seeking an elected position.

Dickerson has worked in the office of revenue for four years.

"I knew the present commissioner was going to retire," Dickerson says. "And I wanted to see what the job involved before I ran."

Dickerson says she has worked in the tax and accounting field for 31 years as a tax technician and bookkeeper. She was self-employed 12 years.

Reed said he has worked privately as a management consultant and spent 20 years in management positions for General Motors Corp. in Detroit.