How to pay monthly interest on savings as an auto-entrepreneur?

I am in auto-entrepreneur micro fiscal, I make my quarterly declaration and pay 23% of income every quarter, i.e. 21.3% social and 1.7% tax liability. I have been in business here since 2007 initially as entreprise individual and changed to auto-entrepreneur from january 2009. My English father died in the in September 2010 and in May 2011 I received my inheritance from his estate.

Initially I paid this money into an offshore account to keep it in stirling as I did not want to exchange it to euro’s due to the poor rates. Half the money was put into a non interest bearing cheque account, and in July 2011 the other half was put into a saving account in the isle of man again remaining in stirling. Anyway I am about to come to the end of the first years interest later this month, and would like to know how I go about declaring this interest earned. From August I will receive interest on a monthly basis.

I bank in France with banque tarneaud, and my manager has told me that as I am in the auto-entrepreneur regime, I am able to include the interest earned from these savings, each quarter if I wish, and simply include it in the income declared for that quarter? By doing this I will pay 23% of the total interest earned in that month/quarter? I have looked at the form that RSI sent me each quarter to make my declaration and there is no seperate heading for this, so can I just add the interest earned in that quarter to my income total and pay 23%?