diff --git a/Rdmp.Core.Tests/DataExport/DataExtraction/ExtractionHoldoutTests.cs b/Rdmp.Core.Tests/DataExport/DataExtraction/ExtractionHoldoutTests.cs
new file mode 100644
index 0000000000..15b17e8094
--- /dev/null
+++ b/Rdmp.Core.Tests/DataExport/DataExtraction/ExtractionHoldoutTests.cs
@@ -0,0 +1,130 @@
+// Copyright (c) The University of Dundee 2018-2023
+// This file is part of the Research Data Management Platform (RDMP).
+// RDMP is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
+// RDMP is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+// You should have received a copy of the GNU General Public License along with RDMP. If not, see <https://www.gnu.org/licenses/>.
+
+using NUnit.Framework;
+using Rdmp.Core.DataExport.DataExtraction.Pipeline;
+using Rdmp.Core.DataFlowPipeline;
+using System;
+using System.IO;
+using Rdmp.Core.ReusableLibraryCode.Checks;
+using Rdmp.Core.ReusableLibraryCode.Progress;
+using System.Data;
+using NUnit.Framework.Internal;
+using Rdmp.Core.DataExport.DataExtraction.Commands;
+using Rdmp.Core.DataExport.DataExtraction.UserPicks;
+using Tests.Common.Scenarios;
+
+namespace Rdmp.Core.Tests.DataExport.DataExtraction;
+
+internal class ExtractionHoldoutTests: TestsRequiringAnExtractionConfiguration
+{
+    private ExtractionHoldout _holdout;
+    private DirectoryInfo _holdoutDir;
+    private DataTable _toProcess;
+    private IExtractCommand _ExtractionStub;
+
+    [SetUp]
+    protected override void SetUp()
+    {
+        base.SetUp();
+        _holdout = new ExtractionHoldout();
+        _holdoutDir = new DirectoryInfo(Path.Combine(TestContext.CurrentContext.WorkDirectory, "Holdout"));
+        Console.WriteLine(Path.Combine(TestContext.CurrentContext.WorkDirectory));
+        if(_holdoutDir.Exists)
+        {
+            _holdoutDir.Delete(true);
+        }
+        _holdoutDir.Create();
+        _toProcess = new DataTable();
+        _toProcess.Columns.Add("FAKE_CHI");
+        _toProcess.Rows.Add(1);
+        _toProcess.Rows.Add(2);
+        _toProcess.Rows.Add(3);
+        _toProcess.Rows.Add(4);
+        _toProcess.Rows.Add(5);
+        _toProcess.Rows.Add(6);
+    }
+
+    [Test]
+    public void NoConfiguration()
+    {
+        var ex = Assert.Throws<Exception>(() => _holdout.Check(ThrowImmediatelyCheckNotifier.Quiet));
+        Assert.IsTrue(ex.Message.Contains("No holdout file location set."));
+    }
+
+    [Test]
+    public void LocationSet()
+    {
+        _holdout.holdoutStorageLocation = _holdoutDir.FullName;
+        var ex = Assert.Throws<Exception>(() => _holdout.Check(ThrowImmediatelyCheckNotifier.Quiet));
+        Assert.IsTrue(ex.Message.Contains("No data holdout count set."));
+    }
+
+    [Test]
+    public void LocationAndCountSet()
+    {
+        _holdout.holdoutStorageLocation = _holdoutDir.FullName;
+        _holdout.holdoutCount = 1;
+        _holdout.Check(ThrowImmediatelyCheckNotifier.Quiet);
+        Console.WriteLine(_holdoutDir.FullName);
+        FileAssert.DoesNotExist(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv"));//todo use the correct name
+    }
+
+    [Test]
+    public void ExtractionHoldoutSingle()
+    {
+        _holdout.holdoutStorageLocation = _holdoutDir.FullName;
+        _holdout.holdoutCount = 1;
+        _ExtractionStub = new ExtractDatasetCommand(_configuration, new ExtractableDatasetBundle(_extractableDataSet));
+        _holdout.PreInitialize(_ExtractionStub, ThrowImmediatelyDataLoadEventListener.Quiet);
+        _holdout.ProcessPipelineData(_toProcess, ThrowImmediatelyDataLoadEventListener.Quiet, new GracefulCancellationToken());
+        _holdout.Dispose(ThrowImmediatelyDataLoadEventListener.Quiet, null);
+        Assert.IsTrue(File.Exists(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv")));
+        String expectedOutput = File.ReadAllText(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv"));
+        Assert.That(expectedOutput, Does.Match("FAKE_CHI\r\n[1-6]\r\n"));
+
+    }
+
+    [Test]
+    public void ExtractionHoldoutPercentage()
+    {
+        _holdout.holdoutStorageLocation = _holdoutDir.FullName;
+        _holdout.holdoutCount = 33;
+        _holdout.isPercentage = true;
+        _ExtractionStub = new ExtractDatasetCommand(_configuration, new ExtractableDatasetBundle(_extractableDataSet));
+        _holdout.PreInitialize(_ExtractionStub, ThrowImmediatelyDataLoadEventListener.Quiet);
+        _holdout.ProcessPipelineData(_toProcess, ThrowImmediatelyDataLoadEventListener.Quiet, new GracefulCancellationToken());
+        _holdout.Dispose(ThrowImmediatelyDataLoadEventListener.Quiet, null);
+        Assert.IsTrue(File.Exists(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv")));
+        String expectedOutput = File.ReadAllText(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv"));
+        Assert.That(expectedOutput, Does.Match("FAKE_CHI\r\n[1-6]\r\n[1-6]\r\n"));
+
+    }
+    [Test]
+    public void ExtractionHoldoutPercentageAppend()
+    {
+        _holdout.holdoutStorageLocation = _holdoutDir.FullName;
+        _holdout.holdoutCount = 33;
+        _holdout.isPercentage = true;
+        _holdout.overrideFile = false;
+        _ExtractionStub = new ExtractDatasetCommand(_configuration, new ExtractableDatasetBundle(_extractableDataSet));
+        _holdout.PreInitialize(_ExtractionStub, ThrowImmediatelyDataLoadEventListener.Quiet);
+        _holdout.ProcessPipelineData(_toProcess, ThrowImmediatelyDataLoadEventListener.Quiet, new GracefulCancellationToken());
+        _holdout.Dispose(ThrowImmediatelyDataLoadEventListener.Quiet, null);
+        Assert.IsTrue(File.Exists(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv")));
+        String expectedOutput = File.ReadAllText(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv"));
+        Assert.That(expectedOutput, Does.Match("FAKE_CHI\r\n[1-6]\r\n[1-6]\r\n"));
+
+        _holdout.PreInitialize(_ExtractionStub, ThrowImmediatelyDataLoadEventListener.Quiet);
+        _holdout.ProcessPipelineData(_toProcess, ThrowImmediatelyDataLoadEventListener.Quiet, new GracefulCancellationToken());
+        _holdout.Dispose(ThrowImmediatelyDataLoadEventListener.Quiet, null);
+        Assert.IsTrue(File.Exists(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv")));
+        expectedOutput = File.ReadAllText(Path.Combine(_holdoutDir.FullName, "holdout_TestTable.csv"));
+        Assert.That(expectedOutput, Does.Match("FAKE_CHI\r\n[1-6]\r\n[1-6]\r\n[1-6]\r\n[1-6]\r\n"));
+
+    }
+
+}
\ No newline at end of file
diff --git a/Rdmp.Core/DataExport/DataExtraction/Pipeline/ExtractionHoldout.cs b/Rdmp.Core/DataExport/DataExtraction/Pipeline/ExtractionHoldout.cs
new file mode 100644
index 0000000000..4a9682f3fd
--- /dev/null
+++ b/Rdmp.Core/DataExport/DataExtraction/Pipeline/ExtractionHoldout.cs
@@ -0,0 +1,252 @@
+// Copyright (c) The University of Dundee 2018-2023
+// This file is part of the Research Data Management Platform (RDMP).
+// RDMP is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
+// RDMP is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+// You should have received a copy of the GNU General Public License along with RDMP. If not, see <https://www.gnu.org/licenses/>.
+
+using Rdmp.Core.Curation.Data;
+using Rdmp.Core.DataExport.DataExtraction.Commands;
+using Rdmp.Core.DataFlowPipeline;
+using Rdmp.Core.DataFlowPipeline.Requirements;
+using Rdmp.Core.ReusableLibraryCode.Checks;
+using Rdmp.Core.ReusableLibraryCode.Progress;
+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Text;
+
+namespace Rdmp.Core.DataExport.DataExtraction.Pipeline;
+
+/// <summary>
+/// <para>
+/// Component for extracting a subset of the extraction data into a holdoput dataset
+/// </para>
+/// </summary>
+public class ExtractionHoldout : IPluginDataFlowComponent<DataTable>, IPipelineRequirement<IExtractCommand>
+{
+    [DemandsInitialization("The % of the data you want to be kelp as holdout data")]
+    public int holdoutCount { get; set; }
+
+    [DemandsInitialization("Use a % as holdout value. If unselected, the actual number will be used.")]
+    public bool isPercentage { get; set; }
+
+    [DemandsInitialization("Write the holdout data to disk. Leave blank if you don't want it exported somewhere")]
+    public string holdoutStorageLocation { get; set; }
+
+    [DemandsInitialization("Set this value to only select data for holdout that is before this date")]
+    public DateTime beforeDate { get; set; }
+
+    [DemandsInitialization("Set this value to only select data for holdout that is after this date")]
+    public DateTime afterDate { get; set; }
+
+    [DemandsInitialization("The column that the before and after date options use to filter holdout data")]
+    public string dateColumn { get; set; }
+
+    //can only filter on strings, not dates
+    [DemandsInitialization("Allows for the filtering of what data can be used as holdout data. The filter only currently supports filtering on string columns, not dates. Filter References https://learn.microsoft.com/en-us/dotnet/api/system.data.dataview.rowfilter?view=net-7.0 and https://learn.microsoft.com/en-us/dotnet/api/system.data.datacolumn.expression?view=net-7.0")]
+    public string whereCondition { get; set; }
+
+    [DemandsInitialization("Overrides any data in the holdout file with new data")]
+    public bool overrideFile { get; set; }
+
+
+    // We may want to automatically reimport into RDMP, but this is quite complicated.
+    // It may be worth having users reimport the catalogue themself until it is proven that this is worth building.
+    //Currently only support writting holdback data to a CSV
+
+
+    private readonly string holdoutColumnName = "_isValidHoldout";
+
+
+    public IExtractDatasetCommand Request { get; private set; }
+
+
+    private bool ValidateIfRowShouldBeFiltered(DataRow row, DataTable toProcess)
+    {
+        if (!string.IsNullOrWhiteSpace(dateColumn))
+        {
+            //had a data column
+            DateTime dateCell;
+            try
+            {
+                dateCell = row.Field<DateTime>(dateColumn);
+            }
+            catch (Exception)
+            {
+                dateCell = DateTime.Parse(row.Field<string>(dateColumn), CultureInfo.InvariantCulture);
+            }
+
+            if (afterDate != DateTime.MinValue && dateCell <= afterDate)
+            {
+                //has date
+                return false;
+            }
+            if (beforeDate != DateTime.MinValue && dateCell >= beforeDate)
+            {
+                //has date
+                return false;
+            }
+        }
+        if (!string.IsNullOrWhiteSpace(whereCondition))
+        {
+            DataTable dt = toProcess.Clone();
+            DataTable dt2 = new();
+            dt.ImportRow(row);
+            using (DataView dv = new DataView(dt))
+            { 
+                dv.RowFilter = whereCondition;
+                dt2 = dv.ToTable();
+                dv.Dispose();
+                
+            }
+            if (dt2.Rows.Count < 1)
+            {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private void FilterRowsBasedOnHoldoutDates(DataTable toProcess)
+    {
+        toProcess.Columns.Add(holdoutColumnName, typeof(bool));
+        foreach (DataRow row in toProcess.Rows)
+        {
+            row[holdoutColumnName] = ValidateIfRowShouldBeFiltered(row, toProcess);
+        }
+    }
+
+    private int GetHoldoutRowCount(DataTable toProcess, IDataLoadEventListener listener)
+    {
+
+        float rowCount = (float)holdoutCount;
+        if (rowCount >= toProcess.Rows.Count && !isPercentage)
+        {
+            listener.OnNotify(this, new NotifyEventArgs(ProgressEventType.Warning, "More holdout data was requested than there is available data. All valid data will be held back"));
+            rowCount = toProcess.Rows.Count;
+        }
+        if (isPercentage)
+        {
+            if (holdoutCount > 100)
+            {
+                listener.OnNotify(this, new NotifyEventArgs(ProgressEventType.Warning, "Holdout percentage was >100%. Will use 100%"));
+                holdoutCount = 100;
+            }
+            rowCount = (float)toProcess.Rows.Count / 100 * holdoutCount;
+        }
+        return (int)Math.Ceiling(rowCount);
+    }
+
+    public void PreInitialize(IExtractCommand request, IDataLoadEventListener listener)
+    {
+        Request = request as IExtractDatasetCommand;
+
+        if (Request == null)
+            return;
+    }
+
+    private void WriteDataTabletoCSV(DataTable dt)
+    {
+        StringBuilder sb = new();
+        string filename = Request.ToString();
+        string path = $"{holdoutStorageLocation}/holdout_{filename}.csv";
+        IEnumerable<string> columnNames = dt.Columns.Cast<DataColumn>().Select(column => column.ColumnName);
+        if (overrideFile || !File.Exists(path))
+        {
+            sb.AppendLine(string.Join(",", columnNames));
+        }
+
+        foreach (DataRow row in dt.Rows)
+        {
+            IEnumerable<string> fields = row.ItemArray.Select(field => field.ToString());
+            sb.AppendLine(string.Join(",", fields));
+        }
+        holdoutStorageLocation.TrimEnd('/');
+        holdoutStorageLocation.TrimEnd('\\');
+
+        if (File.Exists(path) && !overrideFile)
+        {
+
+            using (StreamWriter sw = File.AppendText(path))
+            {
+                sw.WriteLine(sb.ToString());
+            }
+            return;
+
+        }
+
+        File.WriteAllText(path, sb.ToString());
+    }
+
+    public DataTable ProcessPipelineData(DataTable toProcess, IDataLoadEventListener listener, GracefulCancellationToken cancellationToken)
+    {
+        if (toProcess.Rows.Count == 0)
+        {
+            return toProcess;
+        }
+        bool toProcessDTModified = false;
+        if (dateColumn is not null && (afterDate != DateTime.MinValue || beforeDate != DateTime.MinValue))
+        {
+            //we only want to check for valid rows if dates are set, otherwise all rows are valid
+            FilterRowsBasedOnHoldoutDates(toProcess);
+            toProcessDTModified = true;
+        }
+
+        DataTable holdoutData = toProcess.Clone();
+        int foundHoldoutCount = GetHoldoutRowCount(toProcess, listener);
+        var rand = new Random();
+        holdoutData.BeginLoadData();
+        toProcess.BeginLoadData();
+
+        var rowsToMove = toProcess.AsEnumerable().Where(row => !toProcessDTModified || row[holdoutColumnName] is true).OrderBy(r => rand.Next()).Take(foundHoldoutCount);
+        if (rowsToMove.Count() < 1)
+        {
+            listener.OnNotify(this, new NotifyEventArgs(ProgressEventType.Warning, "No valid holdout rows were found. Please check your settings."));
+
+        }
+        foreach (DataRow row in rowsToMove)
+        {
+            holdoutData.ImportRow(row);
+            toProcess.Rows.Remove(row);
+        }
+        holdoutData.EndLoadData();
+        toProcess.EndLoadData();
+
+        if (holdoutStorageLocation is not null && holdoutStorageLocation.Length > 0)
+        {
+            if (toProcessDTModified)
+            {
+                holdoutData.Columns.Remove(holdoutColumnName);
+            }
+            WriteDataTabletoCSV(holdoutData);
+        }
+        if (toProcessDTModified)
+        {
+            toProcess.Columns.Remove(holdoutColumnName);
+
+        }
+
+        return toProcess;
+    }
+
+    public void Check(ICheckNotifier notifier)
+    {
+        if (string.IsNullOrWhiteSpace(holdoutStorageLocation))
+        {
+            notifier.OnCheckPerformed(new CheckEventArgs($"No holdout file location set.", CheckResult.Fail));
+        }
+        if (holdoutCount is 0)
+        {
+            notifier.OnCheckPerformed(new CheckEventArgs($"No data holdout count set.", CheckResult.Fail));
+        }
+    }
+    public void Abort(IDataLoadEventListener listener)
+    {
+    }
+    public void Dispose(IDataLoadEventListener listener, Exception pipelineFailureExceptionIfAny)
+    {
+    }
+}