diff --git a/Corlib.Extensions/System/IO/FileInfo.cs b/Corlib.Extensions/System/IO/FileInfo.cs
index b21ad297..e0a0343c 100644
--- a/Corlib.Extensions/System/IO/FileInfo.cs
+++ b/Corlib.Extensions/System/IO/FileInfo.cs
@@ -1704,7 +1704,23 @@ private static void _KeepFirstLines(FileInfo @this, int count, Encoding encoding
   /// </code>
   /// This example keeps the last 5 lines of "example.txt" and removes all other preceding lines.
   /// </example>
-  public static void KeepLastLines(this FileInfo @this, int count) => _KeepLastLines(@this, count, null, LineBreakMode.AutoDetect);
+  public static void KeepLastLines(this FileInfo @this, int count) => _KeepLastLines(@this, count, null, LineBreakMode.AutoDetect, 0);
+
+  /// <summary>
+  /// Keeps only the specified number of last lines in the file, discarding the rest.
+  /// </summary>
+  /// <param name="this">The <see cref="FileInfo"/> object representing the file.</param>
+  /// <param name="count">The number of lines from the end of the file to keep.</param>
+  /// <param name="offsetInLines">The number of lines to keep at the start of the file.</param>
+  /// <example>
+  /// <code>
+  /// FileInfo fileInfo = new FileInfo("example.txt");
+  /// fileInfo.KeepLastLines(5, 1);
+  /// Console.WriteLine("Last 5 lines and the first kept, others removed.");
+  /// </code>
+  /// This example keeps the last 5 lines and the first of "example.txt" and removes all other preceding lines.
+  /// </example>
+  public static void KeepLastLines(this FileInfo @this, int count, int offsetInLines) => _KeepLastLines(@this, count, null, LineBreakMode.AutoDetect, offsetInLines);
 
   /// <summary>
   /// Keeps only the specified number of last lines in the file, discarding the rest, using the provided encoding.
@@ -1723,7 +1739,28 @@ private static void _KeepFirstLines(FileInfo @this, int count, Encoding encoding
   public static void KeepLastLines(this FileInfo @this, int count, Encoding encoding) {
     Against.ArgumentIsNull(encoding);
 
-    _KeepLastLines(@this, count, encoding, LineBreakMode.AutoDetect);
+    _KeepLastLines(@this, count, encoding, LineBreakMode.AutoDetect, 0);
+  }
+
+  /// <summary>
+  /// Keeps only the specified number of last lines in the file, discarding the rest, using the provided encoding.
+  /// </summary>
+  /// <param name="this">The <see cref="FileInfo"/> object representing the file.</param>
+  /// <param name="count">The number of lines from the end of the file to keep.</param>
+  /// <param name="offsetInLines">The number of lines to keep at the start of the file.</param>
+  /// <param name="encoding">The encoding to use for interpreting the file's content.</param>
+  /// <example>
+  /// <code>
+  /// FileInfo fileInfo = new FileInfo("example.txt");
+  /// fileInfo.KeepLastLines(5, 1, Encoding.UTF8);
+  /// Console.WriteLine("Last 5 lines and the first kept using UTF-8 encoding, others removed.");
+  /// </code>
+  /// This example keeps the last 5 lines  and the first of "example.txt" using UTF-8 encoding and removes all other preceding lines.
+  /// </example>
+  public static void KeepLastLines(this FileInfo @this, int count, int offsetInLines, Encoding encoding) {
+    Against.ArgumentIsNull(encoding);
+
+    _KeepLastLines(@this, count, encoding, LineBreakMode.AutoDetect, offsetInLines);
   }
 
   /// <summary>
@@ -1740,7 +1777,24 @@ public static void KeepLastLines(this FileInfo @this, int count, Encoding encodi
   /// </code>
   /// This example keeps the last 5 lines of "example.txt" based on CrLf line breaks and removes all other preceding lines.
   /// </example>
-  public static void KeepLastLines(this FileInfo @this, int count, LineBreakMode newLine) => _KeepLastLines(@this, count, null, newLine);
+  public static void KeepLastLines(this FileInfo @this, int count, LineBreakMode newLine) => _KeepLastLines(@this, count, null, newLine, 0);
+
+  /// <summary>
+  /// Keeps only the specified number of last lines in the file, discarding the rest, based on the specified line break mode.
+  /// </summary>
+  /// <param name="this">The <see cref="FileInfo"/> object representing the file.</param>
+  /// <param name="count">The number of lines from the end of the file to keep.</param>
+  /// <param name="offsetInLines">The number of lines to keep at the start of the file.</param>
+  /// <param name="newLine">The line break mode to determine the line endings in the file.</param>
+  /// <example>
+  /// <code>
+  /// FileInfo fileInfo = new FileInfo("example.txt");
+  /// fileInfo.KeepLastLines(5, 1, LineBreakMode.CrLf);
+  /// Console.WriteLine("Last 5 lines and the first kept using CrLf line breaks, others removed.");
+  /// </code>
+  /// This example keeps the last 5 lines and the first of "example.txt" based on CrLf line breaks and removes all other preceding lines.
+  /// </example>
+  public static void KeepLastLines(this FileInfo @this, int count, int offsetInLines, LineBreakMode newLine) => _KeepLastLines(@this, count, null, newLine, offsetInLines);
 
   /// <summary>
   /// Keeps only the specified number of last lines in the file, discarding the rest, using the provided encoding and line break mode.
@@ -1760,13 +1814,36 @@ public static void KeepLastLines(this FileInfo @this, int count, Encoding encodi
   public static void KeepLastLines(this FileInfo @this, int count, Encoding encoding, LineBreakMode newLine) {
     Against.ArgumentIsNull(encoding);
 
-    _KeepLastLines(@this, count, encoding, newLine);
+    _KeepLastLines(@this, count, encoding, newLine, 0);
+  }
+
+  /// <summary>
+  /// Keeps only the specified number of last lines in the file, discarding the rest, using the provided encoding and line break mode.
+  /// </summary>
+  /// <param name="this">The <see cref="FileInfo"/> object representing the file.</param>
+  /// <param name="count">The number of lines from the end of the file to keep.</param>
+  /// <param name="offsetInLines">The number of lines to keep at the start of the file.</param>
+  /// <param name="encoding">The encoding to use for interpreting the file's content.</param>
+  /// <param name="newLine">The line break mode to determine the line endings in the file.</param>
+  /// <example>
+  /// <code>
+  /// FileInfo fileInfo = new FileInfo("example.txt");
+  /// fileInfo.KeepLastLines(5, 1, Encoding.UTF8, LineBreakMode.CrLf);
+  /// Console.WriteLine("Last 5 lines and the first kept using UTF-8 encoding and CrLf line breaks, others removed.");
+  /// </code>
+  /// This example keeps the last 5 lines and the first of "example.txt" using UTF-8 encoding and CrLf line breaks, removing all other preceding lines.
+  /// </example>
+  public static void KeepLastLines(this FileInfo @this, int count, int offsetInLines, Encoding encoding, LineBreakMode newLine) {
+    Against.ArgumentIsNull(encoding);
+
+    _KeepLastLines(@this, count, encoding, newLine, offsetInLines);
   }
 
-  private static void _KeepLastLines(FileInfo @this, int count, Encoding encoding, LineBreakMode newLine) {
+  private static void _KeepLastLines(FileInfo @this, int count, Encoding encoding, LineBreakMode newLine, int offsetInLines) {
     Against.ThisIsNull(@this);
     Against.CountBelowOrEqualZero(count);
     Against.UnknownEnumValues(newLine);
+    Against.NegativeValues(offsetInLines);
 
     using var stream = @this.Open(FileMode.Open, FileAccess.ReadWrite, FileShare.None);
     var linePositions = new long[count];
@@ -1778,6 +1855,10 @@ private static void _KeepLastLines(FileInfo @this, int count, Encoding encoding,
           : new(stream, encoding, newLine)
       ;
 
+    var writePosition = reader.PreambleSize;
+    while (offsetInLines-- > 0 && reader.ReadLine()!=null)
+      writePosition = stream.Position;
+
     for (;;) {
       var startOfLine = stream.Position;
       if (reader.ReadLine() == null)
@@ -1792,7 +1873,6 @@ private static void _KeepLastLines(FileInfo @this, int count, Encoding encoding,
       return;
 
     --readPosition;
-    var writePosition = reader.PreambleSize;
     
     const int bufferSize = 64 * 1024;
     var buffer = new byte[bufferSize];
diff --git a/Corlib.Extensions/System/IO/FileInfoExtensions.CustomTextReader.cs b/Corlib.Extensions/System/IO/FileInfoExtensions.CustomTextReader.cs
index 278bafe6..ddc1cc7e 100644
--- a/Corlib.Extensions/System/IO/FileInfoExtensions.CustomTextReader.cs
+++ b/Corlib.Extensions/System/IO/FileInfoExtensions.CustomTextReader.cs
@@ -323,9 +323,9 @@ public Initialized(Stream stream, bool detectEncodingFromByteOrderMark, StringEx
         stream, detectEncodingFromByteOrderMark, null, lineBreakMode) { }
 
       public Initialized(Stream stream, Encoding encoding, StringExtensions.LineBreakMode lineBreakMode = StringExtensions.LineBreakMode.AutoDetect)
-        : this(stream, false, encoding, lineBreakMode) {
-        Against.ArgumentIsNull(encoding);
-      }
+        : this(stream, false, encoding, lineBreakMode) 
+        => Against.ArgumentIsNull(encoding)
+        ;
 
       public long PreambleSize { get; }
 
diff --git a/Tests/Corlib.Tests/System/IO/FileInfoTest.cs b/Tests/Corlib.Tests/System/IO/FileInfoTest.cs
index ab09e30a..e0f5e858 100644
--- a/Tests/Corlib.Tests/System/IO/FileInfoTest.cs
+++ b/Tests/Corlib.Tests/System/IO/FileInfoTest.cs
@@ -335,43 +335,54 @@ public enum TestEncoding {
     [TestCase("ab\nc\x0076def", 1, TestEncoding.Utf8, LineBreakMode.Zx, "ab\nc\x76")]
     [TestCase("ab\nc\0def", 1, TestEncoding.Utf8, LineBreakMode.Null, "ab\nc\0")]
     public void KeepFirstLines(string? input, int count, TestEncoding testEncoding, LineBreakMode newLine, string expected, Type? exception = null)
-      => this._ExecuteTest((f, c, e, l, a) => {
+      => this._ExecuteTest((f, c, e, l, o,a) => {
         if (a)
           f.KeepFirstLines(c, l);
         else
           f.KeepFirstLines(c, e, l);
-      }, input, count, testEncoding, newLine, expected, exception)
+      }, input, count, testEncoding, newLine, 0,expected, exception)
     ;
 
     [Test]
-    [TestCase(null, 1, TestEncoding.Utf8, LineBreakMode.LineFeed, null, typeof(NullReferenceException))]
-    [TestCase("", 0, TestEncoding.Utf8, LineBreakMode.LineFeed, null, typeof(ArgumentOutOfRangeException))]
-    [TestCase("", 1, TestEncoding.Null, LineBreakMode.LineFeed, null, typeof(ArgumentNullException))]
-    [TestCase("abc", 1, TestEncoding.ASCII, (LineBreakMode)short.MinValue, "", typeof(ArgumentException))]
-    [TestCase("abc", 1, TestEncoding.ASCII, LineBreakMode.None, "abc")]
-    [TestCase("abc\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, "abc\n")]
-    [TestCase("abc\ndef", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, "def")]
-    [TestCase("abc\ndef\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, "def\n")]
-    [TestCase("abc\r\ndef", 1, TestEncoding.ASCII, LineBreakMode.CrLf, "def")]
-    [TestCase("abc\r\ndef\r\n", 1, TestEncoding.ASCII, LineBreakMode.CrLf, "def\r\n")]
-    [TestCase("abc\r\ndef", 1, TestEncoding.ASCII, LineBreakMode.All, "def")]
-    [TestCase("abc\r\ndef", 1, TestEncoding.ASCII, LineBreakMode.AutoDetect, "def")]
-    [TestCase("abc\rdef\r", 1, TestEncoding.AutoDetectFromBom, LineBreakMode.CarriageReturn, "def\r")]
-    [TestCase("abc\x000cdef", 1, TestEncoding.UnicodeBigEndian, LineBreakMode.FormFeed, "def")]
-    [TestCase("abc\x0085de\ff", 1, TestEncoding.UnicodeLittleEndianNoBOM, LineBreakMode.NextLine, "de\ff")]
-    [TestCase("abc\x0015de\u0085f", 1, TestEncoding.Utf8, LineBreakMode.NegativeAcknowledge, "de\u0085f")]
-    [TestCase("abc\x2028de\rf", 1, TestEncoding.Utf8NoBOM, LineBreakMode.LineSeparator, "de\rf")]
-    [TestCase("abc\x2029de\nf", 1, TestEncoding.Utf8, LineBreakMode.ParagraphSeparator, "de\nf")]
-    [TestCase("abc\x009Bde\nf", 1, TestEncoding.Utf8, LineBreakMode.EndOfLine, "de\nf")]
-    [TestCase("abc\x0076de\nf", 1, TestEncoding.Utf8, LineBreakMode.Zx, "de\nf")]
-    [TestCase("abc\0de\nf", 1, TestEncoding.Utf8, LineBreakMode.Null, "de\nf")]
-    public void KeepLastLines(string? input, int count, TestEncoding testEncoding, LineBreakMode newLine, string expected, Type? exception = null)
-      => this._ExecuteTest((f, c, e, l, a) => {
-        if (a)
-          f.KeepLastLines(c, l);
-        else
-          f.KeepLastLines(c, e, l);
-      }, input, count, testEncoding, newLine, expected, exception)
+    [TestCase(null, 1, TestEncoding.Utf8, LineBreakMode.LineFeed, 0, null, typeof(NullReferenceException))]
+    [TestCase("", 0, TestEncoding.Utf8, LineBreakMode.LineFeed, 0, null, typeof(ArgumentOutOfRangeException))]
+    [TestCase("", 1, TestEncoding.Null, LineBreakMode.LineFeed, 0, null, typeof(ArgumentNullException))]
+    [TestCase("abc", 1, TestEncoding.ASCII, (LineBreakMode)short.MinValue, 0, "",  typeof(ArgumentException))]
+    [TestCase("abc", 1, TestEncoding.ASCII, LineBreakMode.None, 0, "abc")]
+    [TestCase("abc\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, 0, "abc\n")]
+    [TestCase("abc\ndef", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, 0, "def")]
+    [TestCase("abc\ndef\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, 0, "def\n")]
+    [TestCase("abc\r\ndef", 1, TestEncoding.ASCII, LineBreakMode.CrLf, 0, "def")]
+    [TestCase("abc\r\ndef\r\n", 1, TestEncoding.ASCII, LineBreakMode.CrLf, 0, "def\r\n")]
+    [TestCase("abc\r\ndef", 1, TestEncoding.ASCII, LineBreakMode.All, 0, "def")]
+    [TestCase("abc\r\ndef", 1, TestEncoding.ASCII, LineBreakMode.AutoDetect, 0, "def")]
+    [TestCase("abc\rdef\r", 1, TestEncoding.AutoDetectFromBom, LineBreakMode.CarriageReturn, 0, "def\r")]
+    [TestCase("abc\x000cdef", 1, TestEncoding.UnicodeBigEndian, LineBreakMode.FormFeed, 0, "def")]
+    [TestCase("abc\x0085de\ff", 1, TestEncoding.UnicodeLittleEndianNoBOM, LineBreakMode.NextLine, 0, "de\ff")]
+    [TestCase("abc\x0015de\u0085f", 1, TestEncoding.Utf8, LineBreakMode.NegativeAcknowledge, 0, "de\u0085f")]
+    [TestCase("abc\x2028de\rf", 1, TestEncoding.Utf8NoBOM, LineBreakMode.LineSeparator, 0, "de\rf")]
+    [TestCase("abc\x2029de\nf", 1, TestEncoding.Utf8, LineBreakMode.ParagraphSeparator, 0, "de\nf")]
+    [TestCase("abc\x009Bde\nf", 1, TestEncoding.Utf8, LineBreakMode.EndOfLine, 0, "de\nf")]
+    [TestCase("abc\x0076de\nf", 1, TestEncoding.Utf8, LineBreakMode.Zx, 0, "de\nf")]
+    [TestCase("abc\0de\nf", 1, TestEncoding.Utf8, LineBreakMode.Null, 0, "de\nf")]
+    [TestCase("abc\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, -1, "abc\n",typeof(ArgumentOutOfRangeException))]
+    [TestCase("abc\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, 1, "abc\n")]
+    [TestCase("abc\ndef\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, 1, "abc\ndef\n")]
+    [TestCase("abc\ndef\nghi\n", 1, TestEncoding.ASCII, LineBreakMode.LineFeed, 1, "abc\nghi\n")]
+    public void KeepLastLines(string? input, int count, TestEncoding testEncoding, LineBreakMode newLine, int offset, string expected, Type? exception = null)
+      => this._ExecuteTest((f, c, e, l, o, a) => {
+        if (o != 0) {
+          if (a)
+            f.KeepLastLines(c, o, l);
+          else
+            f.KeepLastLines(c, o, e, l);
+        } else{
+          if (a)
+            f.KeepLastLines(c, l);
+          else
+            f.KeepLastLines(c, e, l);
+        }
+      }, input, count, testEncoding, newLine, offset, expected, exception)
     ;
 
     [Test]
@@ -397,12 +408,12 @@ public void KeepLastLines(string? input, int count, TestEncoding testEncoding, L
     [TestCase("abc\x0076de\nf", 1, TestEncoding.Utf8, LineBreakMode.Zx, "de\nf")]
     [TestCase("abc\0de\nf", 1, TestEncoding.Utf8, LineBreakMode.Null, "de\nf")]
     public void RemoveFirstLines(string? input, int count, TestEncoding testEncoding, LineBreakMode newLine, string expected, Type? exception = null)
-     => this._ExecuteTest((f, c, e, l, a) => {
+     => this._ExecuteTest((f, c, e, l,o, a) => {
        if (a)
          f.RemoveFirstLines(c, l);
        else
          f.RemoveFirstLines(c, e, l);
-     }, input, count, testEncoding, newLine, expected, exception)
+     }, input, count, testEncoding, newLine,0, expected, exception)
    ;
 
     [Test]
@@ -428,15 +439,15 @@ public void RemoveFirstLines(string? input, int count, TestEncoding testEncoding
     [TestCase("ab\nc\x0076def", 1, TestEncoding.Utf8, LineBreakMode.Zx, "ab\nc\x76")]
     [TestCase("ab\nc\0def", 1, TestEncoding.Utf8, LineBreakMode.Null, "ab\nc\0")]
     public void RemoveLastLines(string? input,int count, TestEncoding testEncoding, LineBreakMode newLine,string expected, Type? exception=null) 
-      => this._ExecuteTest((f, c, e, l, a) => {
+      => this._ExecuteTest((f, c, e, l,o, a) => {
         if (a)
           f.RemoveLastLines(c, l);
         else
           f.RemoveLastLines(c, e, l);
-      }, input,count,testEncoding,newLine,expected,exception)
+      }, input,count,testEncoding,newLine,0,expected,exception)
       ;
 
-    private void _ExecuteTest(Action<FileInfo?,int,Encoding?,LineBreakMode,bool> runner, string? input, int count, TestEncoding testEncoding, LineBreakMode newLine, string expected, Type? exception = null) {
+    private void _ExecuteTest(Action<FileInfo?, int, Encoding?, LineBreakMode, int, bool> runner, string? input, int count, TestEncoding testEncoding, LineBreakMode newLine, int offset, string expected, Type? exception = null) {
       Encoding writeEncoding;
       Encoding? readEncoding;
       switch (testEncoding) {
@@ -471,7 +482,7 @@ private void _ExecuteTest(Action<FileInfo?,int,Encoding?,LineBreakMode,bool> run
       if (input == null) {
         file = null;
         ExecuteTest(() => {
-          runner(file, count, readEncoding, newLine,false);
+          runner(file, count, readEncoding, newLine, offset, false);
           return file.ReadAllText(writeEncoding);
         }, expected, exception);
       } else {
@@ -479,13 +490,12 @@ private void _ExecuteTest(Action<FileInfo?,int,Encoding?,LineBreakMode,bool> run
         file = token.File;
         file.WriteAllText(input, writeEncoding);
         ExecuteTest(() => {
-          runner(file, count, readEncoding, newLine,testEncoding==TestEncoding.AutoDetectFromBom);
+          runner(file, count, readEncoding, newLine, offset, testEncoding == TestEncoding.AutoDetectFromBom);
           return file.ReadAllText(writeEncoding);
         }, expected, exception);
       }
     }
 
-
   }
 
 }
\ No newline at end of file