Apply for a voluntary clearance amendment (underpayment) (C2001) Use this form to tell HMRC about voluntary underpayments arising on import of goods From: Contents Who should claim Use form C2001 to make a voluntary disclosure of underpayments arising on the import of goods. This will result in a charge (C18) being raised for the extra duty or VAT due. CHIEF) system to import CPC), this includes: details of the amendment importer item number amended entry number You’ll also need any underpayment details such as the amount of any duty or VAT paid already. In addition, you’ll need details of any: