Tally does allow you to change a reconciliation, however please note that editing a reconciliation should only be required in exceptional circumstances. If you've modified a transaction that has been previously reconciled;  it will become unreconciled this will affect all the balances going forward, meaning all reconciliations subsequently will be affected and need to be re-reconciled. To edit a reconciliation click Bank > Reconcile, then you will see an option of Previous Reconciliations, on this page you then need to press the reconciliation which needs editing. After that click the Edit Reconciliation button at the bottom. You'll then have the opportunity to tick any modified transaction which has been flagged as unreconciled, you may need to press the Refresh Transactions button. To save this reconciliation, just click the Reconcile Now button. Editing a reconciliation does not allow you to change the statement balance. If your balances have changed for this reconciliation period you will need to edit the reconciliation and abandon it, this can be done by going to Bank > Reconcile button next to the account that you're wanting to edit the reconciliation for > Previous Reconciliations button > Edit Reconciliation button at the bottom > Abandon Reconciliation button. You will also have to abandon all reconciliations since that point and re-reconcile from the beginning.