Tasks

• Task 1 Source Retrieval for Scientific Web Claims
• Task 2 Fact-Checking Numerical Claims
• Task 3 Generating Full Fact-Checking Articles

Communication

For communication, please join the Discord Server (https://discord.gg/PEMh4a2YHV) and follow the #checkthat lab-channel.

Registration

Please register to participate in the CheckThat! Lab tasks.

Recent Updates

• 20 May, 2026: Gold labels for all test datasets are available.
• 15 May, 2026: All leaderboards are made public.
• 17 Apr, 2026: an online session will be conducted on 24th of April, 3pm CEST, giving a short overview on each task and a walk-through of the submission system.
• 17 Apr, 2026: Submission site URLs for Task 1 and 2 are available. Please check task specific page.
• 17 Feb, 2026: training data was released.
• 5 Sept, 2025: website is up.

Important Dates

Specific dates will be announced once they are fixed.

• 17 November 2025: Lab registration opens
• December 2025: Release of sample data
• February 2026: Release of the training data
• 23 April 2026: Lab registration closes
• 24 April 2026: Beginning of the evaluation cycle (test sets release)
• 07 May 2026: End of the evaluation cycle (run submission)
• 28 May 2026: Deadline for the submission of working notes [CEUR-WS]
• 29 May – 27 June 2026: Review process of participant papers
• 08 June 2026: Submission of Condensed Lab Overviews [LNCS]
• 15 June 2026: Notification of Acceptance for Condensed Lab Overviews [LNCS]
• 22 June 2026: Camera Ready Copy of Condensed Lab Overviews [LNCS] due
• 30 June 2026: Notification of Acceptance for Participant Papers [CEUR-WS]
• 06 July 2026: Camera Ready Copy of Participant Papers and Extended Lab Overviews [CEUR-WS] due
• 10 July 2026: Regular Conference Registration Ends
• 31 August 2026: Late Conference Registration Ends
• 21-24 September 2026: CLEF 2026 Conference in Jena, Germany

All deadlines are 23:59 in Anywhere on Earth (AOE) timezone.

Organisers

• General:
  • Julia Maria Struß, University of Applied Sciences Potsdam, Germany
  • Sebastian Schellhammer, GESIS - Leibniz Institute for the Social Sciences, Cologne, Germany
• Task 1:
  • Stefan Dietze, GESIS - Leibniz Institute for the Social Sciences, Cologne, Germany
  • Konstantin Todorov, LIRMM, CNRS, University of Montpellier, Montpellier, France
  • Salim Hafid, médialab Sciences Po, Paris, France
• Task 2:
  • Vinay Setty, University of Stavanger, Norway
  • Venktesh V, Delft University of Technology, Nethderlands
• Task 3:
  • Preslav Nakov, MBZUAI, UAE
  • Tanmoy Chakraborty, IIT Delhi, India

PC chairs

• Julia Maria Struß
• Firoj Alam
• Sebastian Schellhammer

Citations

ECIR 2026

@InProceedings{10.1007/978-3-032-21321-1_43,
author="Stru{\ss}, Julia Maria
and Schellhammer, Sebastian
and Dietze, Stefan
and V., Venktesh
and Setty, Vinay
and Chakraborty, Tanmoy
and Nakov, Preslav
and Anand, Avishek
and Chungkham, Primakov
and Hafid, Salim
and Sahnan, Dhruv
and Todorov, Konstantin",
editor="Campos, Ricardo
and Jatowt, Adam
and Lan, Yanyan
and Aliannejadi, Mohammad
and Bauer, Christine
and MacAvaney, Sean
and Anand, Avishek
and Ren, Zhaochun
and Verberne, Suzan
and Bai, Nan
and Mansoury, Masoud",
title="The CLEF-2026 CheckThat! Lab: Advancing Multilingual Fact-Checking",
booktitle="Advances in Information Retrieval",
year="2026",
publisher="Springer Nature Switzerland",
address="Cham",
pages="325--335",
isbn="978-3-032-21321-1"
}

CLEF 2026 LNCS

@InProceedings{clef-checkthat:2026-lncs,
  author = {
     Stru{\ss}, Julia Maria
     and Schellhammer, Sebastian
     and Dietze, Stefan
     and V., Venktesh
     and Setty, Vinay
     and Chakraborty, Tanmoy
     and Nakov, Preslav
     and Anand, Avishek
     and Chungkham, Primakov
     and Hafid, Salim
     and Sahnan, Dhruv
     and Todorov, Konstantin},
  title = {Overview of the {CLEF}-2026 {CheckThat! Lab}: Advancing Multilingual Fact-Checking},
  editor = {
     Hagen, Matthias
     and Potthast, Martin
     and Stein, Benno
     and Schaer, Philipp
     and Zangerle, Eva
     and MacAvaney, Sean
     and Stru{\ss}, Julia Maria
     and Salido, Eva S{\'a}nchez
     and Barr{\'o}n-Cede{\~n}o, Alberto
     and {Alba Garc{\'i}a Seco de Herrera}},
  publisher = {Springer},
  booktitle = {Experimental IR Meets Multilinguality, Multimodality, and Interaction. Proceedings of the Seventeenth International Conference of the CLEF Association (CLEF 2026)},
  year = {2026}
}

CLEF 2026 CEUR papers

Here you find the task-specific papers. They all cross-ref to include information about the volume:

@proceedings{clef2026-workingnotes,
  title = {{CLEF} 2026 Working Notes},
  editor = {
     Salido, Eva S{\'a}nchez
     and Barr{\'o}n-Cede{\~n}o, Alberto
     and {Alba Garc{\'i}a Seco de Herrera}
     and MacAvaney, Sean
     and Stru{\ss}, Julia Maria},
  series = {CLEF~2026},
  address = {Jena, Germany},
  year = 2026
}

Task 1

@inproceedings{clef-checkthat:2026:task1,
   title     = {Overview of the {CLEF-2026 CheckThat!} Lab Task 1 on 
Source Retrieval for Scientific Web Claims},
   author    = {
    Schellhammer, Sebastian and
    Hafid, Salim and
    Kartal, Yavuz Selim and
    Boland, Katarina and
    Dimitrov, Dimitar and
    Todorov, Konstantin and
    Dietze, Stefan
   },
   crossref  = {clef2026-workingnotes}
}

Task 2

@inproceedings{clef-checkthat:2026:task2,
   title     = {Overview of the {CLEF-2026 CheckThat!} Lab Task 2 on 
Fact-Checking Numerical Claims},
   author    = {
      V, Venktesh  and
      Setty, Vinay  and
      Chungkham, Primakov and
      Anand, Avishek 
   },
   crossref  = {clef2026-workingnotes}
}

Task 3

@inproceedings{clef-checkthat:2026:task3,
   title     = {Overview of the {CLEF-2026 CheckThat!} Lab Task 3 on 
Generating Full Fact-Checking Articles},
   author    = {
     Sahnan, Dhruv and Chakraborty, Tanmoy and Nakov, Preslav
   },
   crossref  = {clef2026-workingnotes}
}

CLEF 2026

This edition of the CheckThat! lab is held within CLEF 2026, part of the CLEF initiative.