Take a look here
for information on the tax implications of an overdrawn director's loan account.
If the director's account is still outstanding nine months and one day after the end of the company's accounting period, the company will have to pay a 25% tax charge on the outstanding balance. See section 2 here
. This tax can be reclaimed if and when the loan is repaid partially or fully or released or written off at a specified time after the end of the accounting period or periods during which one of those events happens.
As far as the director is concerned, there will be a taxable benefit on the loan from the company. This should be reported in a P11D. See section 2 here
There will be NIC implications for the director and the company of the loan is released or written off. See section 2 here
. The sum written off will be treated as a dividend on which the director may have to pay a higher rate tax liability. This dividend will need to be disclosed in the director's tax return.
There are no CGT implications.
The only way to minimse the tax liability is to pay as much of the loan off as is possible as soon as possible or to declare a dividend if retained profits allow. Either will help to avoid or reduce the 25% tax charge on the company though there may be higher rate tax implications for the director.
I hope this helps but let me know if you have any further questions.