If you are a director of a small company you may have made private payments using the company's bank account or other resources. Unless these private amounts are reimbursed to the company you would owe money to your company - in accountant speak you would have an overdrawn director's loan account.
There are three principal tax and NIC consequences:
1. Your company may have to make a corporation tax payment based on the overdrawn balance.
2. Unless you pay an HMRC agreed rate of interest on your loan you may suffer a benefit in kind charge.