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Documentation overview
Glossary
Code Lists
XRechnung Fields
Invoice basics
BT-1
BT-2
BT-3
BT-5
BT-6
BT-7
BT-8
BT-10
BT-11
BT-12
BT-14
BT-15
BT-16
BT-17
BT-18
BT-19
BT-21
BT-22
BT-23
BT-24
BT-25
BT-26
Delivery and payment
BT-9
BT-13
BT-20
BT-59
BT-60
BT-61
BT-70
BT-71
BT-72
BT-73
BT-74
BT-75
BT-76
BT-77
BT-78
BT-79
BT-80
BT-81
BT-82
BT-83
BT-84
BT-85
BT-86
BT-87
BT-88
BT-89
BT-90
BT-91
Seller details
BT-27
BT-28
BT-29
BT-30
BT-31
BT-32
BT-33
BT-34
BT-35
BT-36
BT-37
BT-38
BT-39
BT-40
BT-41
BT-42
BT-43
BT-62
BT-63
BT-64
BT-65
BT-66
BT-67
BT-68
BT-69
Buyer details
BT-44
BT-45
BT-46
BT-47
BT-48
BT-49
BT-50
BT-51
BT-52
BT-53
BT-54
BT-55
BT-56
BT-57
BT-58
Discounts and charges
BT-92
BT-93
BT-94
BT-95
BT-96
BT-97
BT-98
BT-99
BT-100
BT-101
BT-102
BT-103
BT-104
BT-105
Taxes and totals
BT-106
BT-107
BT-108
BT-109
BT-110
BT-111
BT-112
BT-113
BT-114
BT-115
BT-116
BT-117
BT-118
BT-119
BT-120
BT-121
BT-122
BT-123
BT-124
BT-125
Line items
BT-126
BT-127
BT-128
BT-129
BT-130
BT-131
BT-132
BT-133
BT-134
BT-135
BT-136
BT-137
BT-138
BT-139
BT-140
BT-141
BT-142
BT-143
BT-144
BT-145
BT-146
BT-147
BT-148
BT-149
BT-150
BT-151
BT-152
BT-153
BT-154
BT-155
BT-156
BT-157
BT-158
BT-159
BT-160
BT-161
BT-162
BT-163
BT-164
BT-165
BT-185
BT-186
ZUGFeRD Profiles
  1. E-Invoicing Resources
  2. XRechnung Fields
  3. BT-11

Reference

Markdown export

BT-11 Project Reference

An identifier for a project, contract, or framework agreement that this invoice relates to. Used to link invoices to specific projects for cost tracking, procurement processes, or contract management purposes.

Quick answerIn plain languageWhat you usually enter hereWhat goes wrong oftenExamples in contextValid ExamplesInvalid ExamplesRelated FieldsXML mapping and field factsXML ImplementationWhy the standard cares about this fieldFAQOfficial sources and tools

Quick answer#

An identifier for a project, contract, or framework agreement that this invoice relates to. Used to link invoices to specific projects for cost tracking, procurement processes, or contract management purposes.

Invoice basics

Core document identifiers, dates, process identifiers, and high-level invoice context.

In plain language#

An identifier for a project, contract, or framework agreement that this invoice relates to. Used to link invoices to specific projects for cost tracking, procurement processes, or contract management purposes.

An identifier for a project, contract, or framework agreement that this invoice relates to. Used to link invoices to specific projects for cost tracking, procurement processes, or contract management purposes.

Essential for organizations managing multiple projects or contracts. Enables proper cost allocation, budget tracking, and financial reporting by project. Particularly important in public procurement where projects must be tracked for compliance and audit purposes.

What you usually enter here#

Free text with alphanumeric characters, hyphens, and underscores

Typical valid values include: PROJECT-2024-001, PROJ-EU-DIGITAL-2024, INFRA-BER-001, IT-MODERNIZATION-2024

Optional according to EN 16931-1. However, may be required by specific procurement regulations or organizational policies for project-based invoicing and cost center allocation.

What goes wrong often#

Avoid values like: , AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA, PROJECT WITH/SPECIAL\CHARS, PROJECT|INVALID*CHARS

Examples in context#

Essential for organizations managing multiple projects or contracts. Enables proper cost allocation, budget tracking, and financial reporting by project. Particularly important in public procurement where projects must be tracked for compliance and audit purposes.

Optional according to EN 16931-1. However, may be required by specific procurement regulations or organizational policies for project-based invoicing and cost center allocation.

Valid Examples#

Use these points as the practical checks for this section.

  • PROJECT-2024-001
  • PROJ-EU-DIGITAL-2024
  • INFRA-BER-001
  • IT-MODERNIZATION-2024
  • BUILD-SCHOOL-MUNICH-23

Invalid Examples#

Use these points as the practical checks for this section.

  • AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
  • PROJECT WITH/SPECIAL\CHARS
  • PROJECT|INVALID*CHARS

Related Fields#

Essential for organizations managing multiple projects or contracts. Enables proper cost allocation, budget tracking, and financial reporting by project. Particularly important in public procurement where projects must be tracked for compliance and audit purposes.

BT-10 Buyer Reference
BT-12 Contract reference
BT-13 Purchase Order Reference
BT-19 Buyer accounting reference

XML mapping and field facts#

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

Field ID:

BT-11

Data Type:

text

Cardinality:

0..1

Requirement:

Optional

Max Length:

300 characters

Since Version:

Optional

XML Implementation#

UBL 2.1 Syntax
/Invoice/cac:ProjectReference/cbc:ID
CII (UN/CEFACT) Syntax
/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:SpecifiedProcuringProject/ram:ID

Why the standard cares about this field#

Business Context

Essential for organizations managing multiple projects or contracts. Enables proper cost allocation, budget tracking, and financial reporting by project. Particularly important in public procurement where projects must be tracked for compliance and audit purposes.

Legal Requirement

Optional according to EN 16931-1. However, may be required by specific procurement regulations or organizational policies for project-based invoicing and cost center allocation.

FAQ#

When should I use the Project Reference (BT-11)?

Use BT-11 when invoicing for work related to a specific project, contract, or framework agreement. This helps the buyer allocate costs correctly and track project expenses.

How does BT-11 differ from BT-13 (Purchase Order Reference)?

BT-11 references the broader project or contract, while BT-13 references the specific purchase order. One project may have multiple purchase orders, but all related invoices share the same project reference.

Is Project Reference mandatory for German public administration?

BT-11 is optional according to EN 16931-1. However, German public authorities may require it for specific procurement projects or framework contracts. Check the tender documents or contract terms.

Can I use internal project codes as Project Reference?

Use the project identifier specified by the buyer or agreed upon in the contract. If no specific format is required, you can use your internal project codes, but ensure they are meaningful to the buyer.

What happens if I provide both BT-11 and BT-12 (Contract Reference)?

Both can be provided when applicable. BT-11 typically references a broader project or program, while BT-12 references the specific contract. Use both when the project spans multiple contracts.

Are there format requirements for Project Reference in Germany?

No specific format is mandated by XRechnung. Use the format specified by the buyer or follow organizational conventions. Common formats include alphanumeric codes with hyphens or underscores.

Official sources and tools#

KoSIT Validator
Invoice Converter
XRechnung Standard
Test Suite
BT-10BT-12
On this page
Quick answerIn plain languageWhat you usually enter hereWhat goes wrong oftenExamples in contextValid ExamplesInvalid ExamplesRelated FieldsXML mapping and field factsXML ImplementationWhy the standard cares about this fieldFAQOfficial sources and tools

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