Bad debts written off is shown as a credit in the sales ledger.
When a business decides to write off a bad debt, it means that they are acknowledging that they are unlikely to receive the payment from the debtor. As a result, they need to remove the debtor's account from their accounts receivable.
To do this, the business will credit the debtor's account in the sales ledger, which reduces the accounts receivable balance. The corresponding entry will be a debit to the bad debts expense account, which represents the cost of doing business with a non-paying customer.
Therefore, bad debts written off is shown as a credit in the sales ledger.