As of 01/01/2024, customs declarations referring to the linking of Warehouse and import, which involve the registration of a new declaration, will not be numbered as before: the sequential number assigned to the declaration per enclosure (5 characters: in deposit declarations and import declarations adapted to the UCC, 6 characters in import DUA declarations) will contain numbers and letters starting from the tenth declaration. The letters Ñ and O are not considered.

In the examples shown, x would be the MRN check digit.

In the MRN column, the sequential number per 5-character enclosure. The character that identifies what type of statement it entails is highlighted in bold. 

Declaration	Enclosure Sequential Number	MRN
Deposit	9	24ES004611 D 00009Rx
Deposit	10	24ES004611 D 0000ARx
DUA import	9	24ES004611 3 000009x
DUA import	11	24ES004611 3 00000Bx
Import CAU	12	24ES004611 I 0000CRx

In 2024, the import DUA and the import declaration adapted to the Union Customs Code (CAU) will coexist. The sequential number per precinct is unique for both types of declarations.