The accounting rules do not "forbid" this type of transaction, however, if you do not refinance OREO property within the provided standards you are required to record the transaction in a certain manner. You are required to continue to carry the new loan as OREO on your CALL report but may carry it as a loan on G/L. In addition, if a gain resulted from the sale the amount may not be taken straight to income but must be deferred. Although some examiners will not balk if the gain is not material. These types of transactions are referred to as "covered transactions" as Andy mentioned. In the past, if the down payment requirement was not met we would monitor the loan until principal payments applied to loan were equal to that of the "required" down payment. In most cases, at that point it was no longer considered a "covered transaction".
You may want to visit with your regulator and the CPA firm that conducts your external audits. They should be able to provide guidance on the transaction in question.
NOTE: Another common error I find when auditing OREO is improper recording of expenses incurred during the holding period. These expenses generally cannot be "netted" from the sale when calculating the gain or loss. IOW - they usually cannot be capitalized.
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An error is not a mistake until you refuse to correct it