diff --git a/astropy/io/ascii/qdp.py b/astropy/io/ascii/qdp.py
index 83a4f004aa37..3c4de017ed4b 100644
--- a/astropy/io/ascii/qdp.py
+++ b/astropy/io/ascii/qdp.py
@@ -60,7 +60,10 @@ def _line_type(line, delimiter=None):
     ValueError: Unrecognized QDP line...
     """
     _decimal_re = r"[+-]?(\d+(\.\d*)?|\.\d+)([eE][+-]?\d+)?"
-    _command_re = r"READ [TS]ERR(\s+[0-9]+)+"
+    # Recognize READ SERR/TERR directives case-insensitively.
+    # Allow tabs/multiple spaces between tokens; anchoring handled by _type_re.
+    _command_re = r"(?i:READ\s+[TS]ERR(?:\s+[0-9]+)+)"
+    # Note: Command directives (READ SERR/READ TERR) are recognized case-insensitively.
 
     sep = delimiter
     if delimiter is None:
diff --git a/astropy/io/ascii/tests/test_qdp_case_insensitive.py b/astropy/io/ascii/tests/test_qdp_case_insensitive.py
new file mode 100644
index 000000000000..764fbdbe97ce
--- /dev/null
+++ b/astropy/io/ascii/tests/test_qdp_case_insensitive.py
@@ -0,0 +1,122 @@
+import numpy as np
+import pytest
+from io import StringIO
+from astropy.table import Table
+
+def _make_qdp_text(cmd1, cmd2):
+     """
+     Construct a minimal QDP text with two directives lines followed by
+     data lines. We flag column 1 with TERR (two-sided errors) and
+     column 3 with SERR (symmetric errors). The data lines then include
+     the values in appropriate sequence:
+       - For TERR on column 1: value, perr, nerr
+       - For SERR on column 3: value, err
+     The middle base column (column 2) has no errors.
+     """
+     return (
+         f"{cmd1}\n"
+         f"{cmd2}\n"
+         "1 0.1 0.2 10 100 5\n"
+         "2 0.11 0.22 20 200 6\n"
+     )
+@pytest.mark.parametrize(
+     "cmds",
+     [
+         ("READ TERR 1", "READ SERR 3"),     # uppercase
+         ("read terr 1", "read serr 3"),     # lowercase
+         ("ReAd TeRr 1", "rEaD sErR 3"),     # mixed case
+     ],
+)
+def test_qdp_command_case_insensitive(cmds):
+     text = _make_qdp_text(*cmds)
+     # Explicit names: 'a', 'b', 'c'
+     t = Table.read(StringIO(text), format="ascii.qdp", names=["a", "b", "c"])
+ 
+     # Column presence
+     assert "a" in t.colnames
+     assert "b" in t.colnames
+     assert "c" in t.colnames
+     assert "a_perr" in t.colnames
+     assert "a_nerr" in t.colnames
+     assert "c_err" in t.colnames
+ 
+     # Values
+     assert np.allclose(t["a"], [1.0, 2.0])
+     assert np.allclose(t["a_perr"], [0.1, 0.11])
+     assert np.allclose(t["a_nerr"], [0.2, 0.22])
+     assert np.allclose(t["b"], [10.0, 20.0])
+     assert np.allclose(t["c"], [100.0, 200.0])
+     assert np.allclose(t["c_err"], [5.0, 6.0])
+ 
+
+def test_qdp_command_case_insensitive_no_names():
+     # Lowercase directives to exercise case-insensitive detection
+     text = _make_qdp_text("read terr 1", "read serr 3")
+     t = Table.read(StringIO(text), format="ascii.qdp")
+ 
+     # Default behavior: base column names are auto-generated (e.g., col1..)
+     # Error columns should be created accordingly.
+     assert "col1" in t.colnames
+     assert "col2" in t.colnames
+     assert "col3" in t.colnames
+     assert "col1_perr" in t.colnames
+     assert "col1_nerr" in t.colnames
+     assert "col3_err" in t.colnames
+ 
+     assert np.allclose(t["col1"], [1.0, 2.0])
+     assert np.allclose(t["col1_perr"], [0.1, 0.11])
+     assert np.allclose(t["col1_nerr"], [0.2, 0.22])
+     assert np.allclose(t["col2"], [10.0, 20.0])
+     assert np.allclose(t["col3"], [100.0, 200.0])
+     assert np.allclose(t["col3_err"], [5.0, 6.0])
+ 
+ 
+def test_qdp_command_uppercase_unchanged():
+    # Uppercase as per existing behavior; ensure unchanged
+    text = _make_qdp_text("READ TERR 1", "READ SERR 3")
+    t = Table.read(StringIO(text), format="ascii.qdp", names=["a", "b", "c"])
+
+    assert "a_perr" in t.colnames
+    assert "a_nerr" in t.colnames
+    assert "c_err" in t.colnames
+    assert np.allclose(t["a_perr"], [0.1, 0.11])
+    assert np.allclose(t["a_nerr"], [0.2, 0.22])
+    assert np.allclose(t["c_err"], [5.0, 6.0])
+
+
+def test_qdp_directives_with_tabs_and_spaces():
+    # Mix tabs and multiple spaces between tokens in directives
+    cmd1 = "READ\tTERR\t1\t"
+    cmd2 = "READ   SERR    3   "
+    text = _make_qdp_text(cmd1, cmd2)
+    t = Table.read(StringIO(text), format="ascii.qdp", names=["a", "b", "c"])
+
+    assert "a_perr" in t.colnames and "a_nerr" in t.colnames
+    assert "c_err" in t.colnames
+    assert np.allclose(t["a"], [1.0, 2.0])
+    assert np.allclose(t["a_perr"], [0.1, 0.11])
+    assert np.allclose(t["a_nerr"], [0.2, 0.22])
+    assert np.allclose(t["b"], [10.0, 20.0])
+    assert np.allclose(t["c_err"], [5.0, 6.0])
+
+
+def test_qdp_directives_with_trailing_whitespace_and_comment_line():
+    # Directives with trailing whitespace and a following comment line
+    cmd1 = "read terr 1   \t"
+    cmd2 = "READ SERR 3   "
+    text = (
+        f"{cmd1}\n"
+        f"{cmd2}\n"
+        "! post-directive comment\n"
+        "1 0.1 0.2 10 100 5\n"
+        "2 0.11 0.22 20 200 6\n"
+    )
+
+    t = Table.read(StringIO(text), format="ascii.qdp", names=["a", "b", "c"])
+
+    # Ensure comment line does not interfere with line-type detection
+    assert "a_perr" in t.colnames and "a_nerr" in t.colnames
+    assert "c_err" in t.colnames
+    assert np.allclose(t["a"], [1.0, 2.0])
+    assert np.allclose(t["b"], [10.0, 20.0])
+    assert np.allclose(t["c_err"], [5.0, 6.0])