This thesis presents a comparison between customs procedures 40 and 42. I have described taxable persons, the process of obtaining a VAT identification number and the obligations and duties that taxable persons must fulfil upon obtaining it. I will present the EORI number, which is obligatory for the implementation of customs procedures in any country of the European Union. I have touched on the customs procedures carried out in the customs territory of the European Union, their main characteristics and everything necessary to carry out an individual procedure. I have explained the procedure for setting the customs tariff and touched on the deferral of payment and insurance of a potential customs debt. I have paid more attention to the release of goods for free circulation on payment of customs duties and VAT and the release for free circulation and entry for home use of goods which are the subject of a VAT-exempt supply to another Member State. I have presented new rules on proving compliance with customs procedure 42 and key differences between procedures 40 and 42. Finally, I have explained the possibility of correcting the incorrect information given in the summary customs declaration.