Independent Health made a mistake in a letter it sent to WNY Immediate Care, prompting the health insurer to delay a deadline -- by a full year -- it had imposed to settle a dispute over fees.

That means the threat of much-higher costs to Independent Health members who use WNY Immediate Care centers has been put off for the next year, as the two sides continue to work on an agreement.

Independent Health on Friday had announced that WNY Immediate Care would be considered a "nonparticipating provider" for all lines of business unless an agreement was reached by Dec. 31.

On Monday, WNY Immediate Care released a copy of a letter its executives received from Independent Health, dated June 1, stating Independent Health was formally giving "notice of nonrenewal" of the agreement, effective 12:01 a.m. on Dec. 31, 2012 -- not 2011. The letter was signed by Dr. Michael W. Cropp, Independent Health's president.

Joseph P. DiVincenzo, vice president, general counsel and compliance officer, said Friday he was "shocked" by the deadline Independent Health had set for the end of this month, because he said the June 1 letter indicated the contract would be honored until the end of 2012. (WNY Immediate Care had declined to release a copy of the letter on Friday, but decided to release it Monday.)

Independent Health called the Dec. 31, 2012, nonrenewal date a "typographical error," but said it would honor that date as its new agreement-renewal deadline. As a result, WNY Immediate Care will remain a "participating provider" through the end of 2012.

"Since beginning discussions in April and issuing the letter in June and throughout our subsequent negotiations, we were explicit with our intention to non-renew our agreement if they remained unwilling to accept our community fee schedule for 2012," Independent Health said in a statement. "The letter does not change our position that WNY Immediate Care's fees are excessive and need to be in line with our community fee schedule for all other urgent care centers."

WNY Immediate Care has five urgent-care medical centers in Buffalo Niagara, and eight altogether. They are managed by the Exigence Group, a health care management organization based in Amherst.

Independent Health said only about 1.5 percent of its members, or about 5,000 subscribers, have used a WNY Immediate Care center this year.

Independent Health says it wants WNY Immediate Care to agree to a contract that would place its reimbursement in line with other urgent-care centers.

WNY Immediate Care said it has not asked for any rate increases despite "yearly and significant increases in the premiums (Independent Health) has demanded of its subscribers during the same period."

WNY Immediate Care said there is no expiration date in the agreement between itself and Independent Health.