Yes as you have written confirmation that the enquiry is closed.
the extract from the COP9 states - note that it is my underlining:-
Concluding the investigationIf our investigation finds nothing wrong with your tax affairs, we will let you know that our investigation has finishedIf we find something wrong and you have made a full disclosure, we will accept a money settlement. So if you make a full confession in response to `Hansard', we will not seek to prosecute you even if we consider that you have committed serious tax fraud.
When seeking a money settlement we will try to reach an agreed figure with you covering the amount of tax, interest and penalties we believe are due. We will only suggest adjustments that we consider to be reasonable in the light of the information we hold. You should ask us to explain if you do not understand any of the figures we may propose.
If we cannot reach agreement we may seek to determine formally the tax, interest and penalties we consider appropriate.
We can use the information or documents that you provided during the investigation in any proceedings to determine your liability to tax, interest and penalties.
Where there have been errors or omissions in your accounts or tax returns we will ask you to sign a Certificate of Full Disclosure confirming that you have now declared all your taxable income, gains and other duties. We will not ask for a certificate if the investigation showed nothing wrong.
We will take a very serious view if you sign a Certificate of Full Disclosure you know to be false. You should consider the certificate very carefully before signing it. If you sign a certificate you know is false, you may be liable to prosecution.
You should always make sure you understand what, if anything, was wrong with your accounts or tax returns. You should ask your professional adviser or us what you need to do to make sure you get them right in the future.
So I hope that this helps you