公司在收钱的时候并不是所有的付款者都能按时按量付清款项, 这时就会出现坏账(bad debt), bad debt记录在支出费用（expense）里面
例子：On 16 March 2010, the business was informed that a debtor was bankrupt, and of the $400 owed by Micari, only $40 would be received
这时就要writing off a bad debt
March 16 Bad debts 360
Debtors control 360
General ledger
Bad debts (E)
Date | Cross-reference | Amount$ | Date | Cross-reference | Amount$ |
Mar. 31 | Debtors control | 360 |
Debtors control (A)
Date | Cross-reference | Amount$ | Date | Cross-reference | Amount$ |
Mar. 1 | Balance | 8000 | Mar. 31 | Bank/Disc. Exp. | 3000 |
Mar. 31 | Bad debts | 360 |
对于balance sheet的影响就是Assets减少（Debtors control）, 同时owner’s equity减少（bad debts expense decreases net profit）
在会计记帐的时候，可能会出现记录错误的情况，这时就需要更正
例子：On 31 July 2005, it was discovered that $400 Wages was incorrectly recorded as Electricity, and that drawings of stock worth $250 had been recorded as advertising.
General journal
Date Details Debit Credit
July 31 Wages expense 400
Electricity expense 400
July 31 Drawings 250
Advertising 250
更正的方法就是把本身该记录的项目记录在相应的账目下，例如工资属于支出费用，记录在Debit下面，然后同时把记错的项目撤销掉，例如这里电费多录入了400，现在就记录在Credit下面，之前记错的和后来更改的就正好抵消了
