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An audit is a process of verification that the implementation of the programme is in line with the EU regulations, national and programme rules.

There are three types of audits performed by the Audit Authorities (AA): system audits, audits of operations, and audits of accounts (the so-called “trilogy of audits”). These audits must be finalised for the AA to be able to issue its annual audit opinion (to be submitted by 15 February following the year after the accounting year concerned). The description and results of the auditing exercises are presented to the EC in the Annual Control Reports.

Publication | Roadmap for the assurance package in 2021-2027

Where to start

Check the descriptions and key resources for each part of the trilogy of audits below.

What we are working on

On 11-12 June, we will organize an annual event for Audit Authorities. If you have a question or comment, please reach out to the Interact colleagues listed below. 


For more information please contact Przemyslaw Kniaziuk.

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Exchange Community

Interact offers an online space for Audit authorities to share information and exchange. If you would like to learn more about this, please contact Przemyslaw Kniaziuk.

If you are already a member of the Community, you can access it here.

System audits

Interact, together with a dedicated working group that includes representatives of AAs, MAs and the EC, developed a set of harmonised system audit checklists (from key requirement 1 to 10) tailored to Interreg. The checklists provide a framework for system audit work and to share some information and guidance related to this task. The checklist follows the structure tof the Methodological note for the Assessment of Management and control systems in the Member States and presents example questions that can be asked when performing the check of each assessment criterion.

Checklist | Interreg system audit checklists

Publication | Methodological note for the Assessment of Management and control systems in the Member States

Audit of operations and common sample

Interact in cooperation with a dedicated group of AAs and MAs developed a report template for the audit of operations. It is a model that can be adjusted to the individual needs.

Common sample for Interreg is a new tool to reduce the number of audits of operations which in the 2014-2020 programming period was unproportionally high to the expenditure attributed to Interreg programmes.

The 2021-2027 Interreg Regulation provides for the legal basis for the European Commission to select an EU level common sample for all Interreg programmes also the ones with external sources of funding.  In general, all Interreg programmes should join the common sample so that the system is functional. The minimum sample sizes selected by the EC per programme are:

  • 3 partners for programmes with less than 500 partners and
  • 5 partners for programmes with 500 or more partners.

Programmes themselves must provide the necessary data for the selection of a common sample to the Commission by the deadline established in the regulation (1 August at the latest). The sampling unit is the cumulative expenditure declared in the accounting year by a project partner in an operation, as declared to the Commission. If a project partner is involved in several operations, the audit is limited to the sampled operation.

The data structured as in the data exchange template can be submitted in the SFC 2021 by MA or AA but in any case, the set of figures must be reconciliated (the actual figures must be confirmed by MA and AA). One month later, the Commission will inform the AAs on the common sample selected (partners and their operation(s) to be audited). The programmes may opt for submitting the common sample earlier (early cut-off date). On one hand, this gives AA more time to perform audits on operations, but on the other hand, the EC leaves itself the possibility to increase the initial (3/5 partners) sample when the totality of data has been provided at the latest on 1 August by all the programmes. In this case, additional, late audits on operations by AA might be needed as the sample might increase. Also, if programmes opt for an early submission of data, it is recommended not to send additional payment applications to the EC.

Q&A on common sample for audit of operations

Template for data exchange

Common sample - Information for Interreg Programmes

SFC manual_Common sample module


Audit of accounts

The AA must provide an annual audit opinion including, among others, an opinion on whether the accounts give a true and fair view, and a statement as to whether the audit work puts in doubt the assertions made in the management declaration on the proper presentation of the accounts, their completeness and accuracy.  

The methodology of audit of accounts is presented here:

Methodological Note on the Preparation, Submission, Examination and Audit of Accounts programming period 2021-2027

Annual control report

The Annual Control Report is another element of the assurance package documents (the accounts, management declaration, annual audit opinion and annual control report).

As other documents of the assurance package the ACR has to be submitted by 15 February following the year after the accounting year concerned.

The structure of the ACR is described in the following:

Methodological note on the annual control report, audit opinion and treatment of errors