Reasons for not agreeing trial balance:

The debit total of trial balance should be equal to credit total. Sometimes, they are not equal and it is assumed that there are some errors in books of account. Some of the reasons of errors may be as follows:

1. Trial balance will disagree if a transaction is posted in one side of an account and omitted to post it in the another side of another account.
2. If wrong amount is posted in ledger accounts, the trial balance will not agree.
3. When an amount is posted wring side say in debit side instead of credit side, the trial balance will not agree.
4. Sometime, a transaction may be posted twice in the ledger accounts. As a result, the total of a trial balance will not be equal.
5. Disagreement of a trial balance may be caused by the wrong totaling or balancing of ledger accounts.
6. While totaling the figure of subsidiary books there may arise some errors that will cause disagreement of trial balance.
7. Omission to post a ledger balance also causes the disagreement of a trial balance.
8. If there is wrong in totaling of trial balance, a trial balance will disagree.
9. Another cause of disagreement of a trial balance may be the error made in carrying forward the total from one page to another.