Very often, the transactions reported in the Intrastat return are standard sales from one taxable person to another. However, a number of less common scenarios have specific reporting requirements.
These scenarios are reported by specific nature of transaction codes. These codes are made up of two digits, the first one providing general information and the second one, if applicable, giving more details about the specific scenario.
HMRC publishes detailed guidelines about your Intrastat return, Section 6. How to complete your Suplementary Declaration provides all possible scenarios for your nature of transaction combinations.