A standard authorised overdraft, when used responsibly and within the agreed limit, usually doesn't have a direct negative impact on your credit score. However, consistently maxing out your overdraft or going into unauthorised overdraft (exceeding your agreed limit) can be harmful. Unauthorised overdrafts can lead to fees, and if these aren't paid, the bank could report the missed payments to credit bureaus, negatively impacting your credit score. Also, regularly relying heavily on your overdraft can be viewed as poor financial management by potential lenders.