CDS12056Relation error: the combination of elements is not allowed
Two values on the declaration cannot be used together, or one value requires another that is missing.
What to check for CDS12056
- Document codes against their document status codes.
- Additional procedure codes that require a further code alongside them.
- Whether the customs procedure can be used with authorisation by declaration.
See CPC codes for UK imports for how procedure codes combine.
What to check across the Relation, authorisation and sequence errors
Two elements, or a value and a rule, disagree. Read both elements together: completing one element with a particular code often requires another value, and the fault is frequently in the element you did not change. The family also covers parties and authorisations that are not recognised, references that must be unique, and messages sent out of sequence.
What does CDS12056 mean?
CDS12056 is a relation error: the combination of two values is not allowed, or one value requires another that is missing. HMRC's examples include a document code with an incompatible status and an additional procedure code that needs a second code. Check document and procedure code combinations first.
A declaration that clears CDS can still be wrong
The free eligibility checker confirms your import activity and whether a free post-clearance audit applies. No data upload, no commitment.
Source: HMRC, Customs Declaration Service error codes, Open Government Licence v3.0. GOV.UK publication · Licence