Both "Cancel Transaction" and "Write Off" of an invoice generates a Credit Note to knock off an amount owing. So, what's the different between the two?
When a mistake made in a sales invoice or a return of goods and services you can use a cancel transaction (under the Command menu > Adjustments). MoneyWorks creates a reverse transaction to adjust the income, tax, receivable, and the quantity sold.
When an invoice has turned into bad debts, write off is used. A write-off entry debits the expense and credit the accounts receivable.
You can refer to the MoneyWorks v7 user guide page 155, Adjustments, to have a better understanding of when and how to use the adjustment function such as Cancel Transaction, Contra, and Write Off.