A journal entry reversal is an entry that undoes a previous journal entry by posting the same amounts to the same accounts with the debits and credits exchanged. It is used in two situations. The first is routine: period-end accruals and estimates are reversed at the start of the next period so that, when the real invoice or payment is recorded, the expense is not counted twice. Entries of this kind are often flagged to reverse automatically and are described under reversing entry.
The second is correction. Accounting systems do not normally allow a posted entry to be deleted, since that would break the audit trail. An entry made in error is reversed, and a correct entry is posted in its place. The reversal should refer to the original entry, state the reason, and go through journal entry approval. If the original period has been closed, the reversal is posted in the current period.