If the asset is a fixed asset, verify that it has been depreciated through the end of the last reporting period. If the asset had previously been classified as held for sale, it should not have been depreciated since it was classified as such, which is acceptable.
Verify that the amount of accumulated depreciation recorded for the asset matches the underlying depreciation calculation. If there is a difference (usually because the accumulated depreciation figure is too low), reconcile the two amounts and adjust the accounting records as necessary.
The original purchase price of the asset, minus all accumulated depreciation and any accumulated impairment charges, is the carrying amount of the asset. Subtract this carrying amount from the sale price of the asset. If the remainder is positive, it is a gain. If the remainder is negative, it is a loss.
If there is a gain, the entry is a debit to the accumulated depreciation account, a credit to a gain on sale of assets account, and a credit to the asset account. If there is a loss, the entry is a debit to the accumulated depreciation account, a debit to the loss on sale of assets account, and a credit to the asset account.
If the consideration paid is scheduled to be paid well into the future, it is likely that a component of the sale price actually represents interest income, which you could consider breaking out from the gain or loss calculation and reporting separately.
As an example of a gain or loss calculation, ABC Company has a machine that originally cost $80,000 and against which $65,000 of accumulated depreciation has been recorded, resulting in a carrying amount of $15,000. ABC sells the machine for $18,000. The entry to record the transaction is a debit of $65,000 to the accumulated depreciation account, a debit of $18,000 to the cash account, a credit of $80,000 to the fixed asset account, and a credit of $3,000 to the gain on sale of assets account. The net effect of this entry is to eliminate the machine from the accounting records, while recording a gain and the receipt of cash.