Mis stated loan in prior year - too much dividend paid

Hello

I have just found out that a loan has been mis stated in my new clients accounts. Basically, what should have been stated as a loan has been stated as income in 2011/12. As a result his profit has decreased and he should not have taken the level of dividends that he did. I just need to know how to deal with the dividend situ...do I need to notify anyone? It has no effect on VAT as he is flat rate and he paid no corp tax in that year.

If someone could let me know the implications of this mis statement I would be very grateful.

Many Thanks