Questions about cash-flow projections provided the ammunition for the latest skirmish Monday between the offices of Erie County Executive Mark C. Poloncarz and County Comptroller Stefan I. Mychajliw.

It began with an email from Deputy County Comptroller Gregory G. Gach, whose position Poloncarz sought to eliminate in his 2013 budget, to Robert W. Keating, the county’s budget director. Keating said Gach declared that at the close of business Friday, the county had a negative cash balance of $655,243, a figure that Keating said was subsequently corrected to $271,165.

Keating fired a letter back to Mychajliw, saying the offices of the executive and comptroller had agreed to resolve a cash-flow shortage by delaying a payment to Erie County Medical Center Corp. for a month, which would give the county a positive cash balance of $13,874,462 at the end of January.

“However,” Keating added, “your latest numbers show a negative balance just one day later after the close of the month for a divergence totaling $14 million. This wild swing is troubling, as is the suddenness and late nature with which your office alerted me.”

Keating then inquired about whether the problem was caused “by delayed state reimbursements and advances, as you indicated before the Legislature’s Finance and Management Committee on Jan. 31,” and what the Comptroller’s Office was doing to remedy things until the county gets $35 million in sales tax receipts Wednesday.

Gach, in a letter dated today and released Monday night, confirmed the end-of-the-month cash balance projections and noted that the county had $18,915,726 on hand at the end of the day Jan. 31. But, he added, more than $15 million in checks were released on the first day of February “along with various other cash transactions resulting in the bank balance [of minus] $275,165.20.”

Gach, noting that the Comptroller’s Office now provides weekly cash-flow updates instead of monthly reports, as it did when Poloncarz was comptroller, additionally told Keating: “The difficulty lies in your office’s basic misunderstanding of cash flows. At this time of year, the county is historically low on its cash balances.”