diff --git a/ql/src/java/org/apache/hadoop/hive/ql/parse/type/HiveFunctionHelper.java b/ql/src/java/org/apache/hadoop/hive/ql/parse/type/HiveFunctionHelper.java
index 556388c71914..9988a0294ad7 100644
--- a/ql/src/java/org/apache/hadoop/hive/ql/parse/type/HiveFunctionHelper.java
+++ b/ql/src/java/org/apache/hadoop/hive/ql/parse/type/HiveFunctionHelper.java
@@ -73,6 +73,7 @@
 import org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPEqualNS;
 import org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPNotEqualNS;
 import org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPOr;
+import org.apache.hadoop.hive.ql.udf.generic.NonNullableReturnTypeUDF;
 import org.apache.hadoop.hive.ql.udf.generic.GenericUDTF;
 import org.apache.hadoop.hive.serde2.objectinspector.ConstantObjectInspector;
 import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
@@ -135,12 +136,20 @@ public RelDataType getReturnType(FunctionInfo fi, List<RexNode> inputs)
       inputsOIs[i] = createObjectInspector(inputs.get(i));
     }
     // 2) Initialize and obtain return type
-    ObjectInspector oi = fi.getGenericUDF() != null ?
-        fi.getGenericUDF().initializeAndFoldConstants(inputsOIs) :
+    GenericUDF genericUDF = fi.getGenericUDF();
+    ObjectInspector oi = genericUDF != null ?
+        genericUDF.initializeAndFoldConstants(inputsOIs) :
         fi.getGenericUDTF().initialize(inputsOIs);
     // 3) Convert to RelDataType
-    return TypeConverter.convert(
+    RelDataType returnType = TypeConverter.convert(
         TypeInfoUtils.getTypeInfoFromObjectInspector(oi), rexBuilder.getTypeFactory());
+    // Hive has no concept of non-nullable types, but some UDFs (e.g. IS NULL) always return
+    // non-nullable BOOLEAN, which Calcite's RexSimplify asserts via validateStrongPolicy.
+    if (genericUDF instanceof NonNullableReturnTypeUDF) {
+      returnType = rexBuilder.getTypeFactory().createTypeWithNullability(returnType, false);
+    }
+    
+    return returnType;
   }
 
   /**
diff --git a/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNotNull.java b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNotNull.java
index 3cb0e8ea5a48..99a64a9aeb2a 100644
--- a/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNotNull.java
+++ b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNotNull.java
@@ -37,7 +37,7 @@
     value = "_FUNC_ a - Returns true if a is not NULL and false otherwise")
 @VectorizedExpressions({IsNotNull.class, SelectColumnIsNotNull.class})
 @NDV(maxNdv = 2)
-public class GenericUDFOPNotNull extends GenericUDF {
+public class GenericUDFOPNotNull extends GenericUDF implements NonNullableReturnTypeUDF {
   private final BooleanWritable result = new BooleanWritable();
 
   @Override
diff --git a/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNull.java b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNull.java
index d0c363d31dee..d75f123285db 100644
--- a/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNull.java
+++ b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPNull.java
@@ -36,7 +36,7 @@
 @Description(name = "isnull", value = "_FUNC_ a - Returns true if a is NULL and false otherwise")
 @VectorizedExpressions({IsNull.class, SelectColumnIsNull.class})
 @NDV(maxNdv = 2)
-public class GenericUDFOPNull extends GenericUDF {
+public class GenericUDFOPNull extends GenericUDF implements NonNullableReturnTypeUDF {
   private final BooleanWritable result = new BooleanWritable();
 
   @Override
diff --git a/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/NonNullableReturnTypeUDF.java b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/NonNullableReturnTypeUDF.java
new file mode 100644
index 000000000000..04ae8a09b802
--- /dev/null
+++ b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/NonNullableReturnTypeUDF.java
@@ -0,0 +1,28 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hive.ql.udf.generic;
+
+/**
+ * Interface for UDFs that always return a non-nullable datatype
+ * (e.g. {@code IS NULL}, {@code IS NOT NULL}).
+ */
+public interface NonNullableReturnTypeUDF {
+}
+
+
diff --git a/ql/src/test/queries/clientpositive/is_null_is_not_null_nested.q b/ql/src/test/queries/clientpositive/is_null_is_not_null_nested.q
new file mode 100644
index 000000000000..267b0f8134d4
--- /dev/null
+++ b/ql/src/test/queries/clientpositive/is_null_is_not_null_nested.q
@@ -0,0 +1,28 @@
+-- Tests for nested IS NULL / IS NOT NULL predicates.
+-- (name IS NULL) IS NULL should simplify to FALSE since IS NULL always returns a non-nullable BOOLEAN.
+-- (name IS NOT NULL) IS NULL should simplify to FALSE for the same reason.
+
+CREATE TABLE t_is_null_nested (id INT, name STRING);
+
+INSERT INTO t_is_null_nested VALUES
+  (1, 'alice'),
+  (2, NULL);
+
+-- always FALSE
+SELECT id, (name IS NULL) IS NULL FROM t_is_null_nested ORDER BY id;
+
+-- always FALSE
+SELECT id, (name IS NOT NULL) IS NULL FROM t_is_null_nested ORDER BY id;
+
+-- always TRUE
+SELECT id, (name IS NULL) IS NOT NULL FROM t_is_null_nested ORDER BY id;
+
+-- always TRUE
+SELECT id, (name IS NOT NULL) IS NOT NULL FROM t_is_null_nested ORDER BY id;
+
+-- no rows should be filtered out
+SELECT id FROM t_is_null_nested WHERE (name IS NULL) IS NOT NULL ORDER BY id;
+
+-- should filter out all rows
+SELECT id FROM t_is_null_nested WHERE (name IS NULL) IS NULL ORDER BY id;
+
diff --git a/ql/src/test/results/clientpositive/llap/is_null_is_not_null_nested.q.out b/ql/src/test/results/clientpositive/llap/is_null_is_not_null_nested.q.out
new file mode 100644
index 000000000000..02930bfd15e5
--- /dev/null
+++ b/ql/src/test/results/clientpositive/llap/is_null_is_not_null_nested.q.out
@@ -0,0 +1,80 @@
+PREHOOK: query: CREATE TABLE t_is_null_nested (id INT, name STRING)
+PREHOOK: type: CREATETABLE
+PREHOOK: Output: database:default
+PREHOOK: Output: default@t_is_null_nested
+POSTHOOK: query: CREATE TABLE t_is_null_nested (id INT, name STRING)
+POSTHOOK: type: CREATETABLE
+POSTHOOK: Output: database:default
+POSTHOOK: Output: default@t_is_null_nested
+PREHOOK: query: INSERT INTO t_is_null_nested VALUES
+  (1, 'alice'),
+  (2, NULL)
+PREHOOK: type: QUERY
+PREHOOK: Input: _dummy_database@_dummy_table
+PREHOOK: Output: default@t_is_null_nested
+POSTHOOK: query: INSERT INTO t_is_null_nested VALUES
+  (1, 'alice'),
+  (2, NULL)
+POSTHOOK: type: QUERY
+POSTHOOK: Input: _dummy_database@_dummy_table
+POSTHOOK: Output: default@t_is_null_nested
+POSTHOOK: Lineage: t_is_null_nested.id SCRIPT []
+POSTHOOK: Lineage: t_is_null_nested.name SCRIPT []
+PREHOOK: query: SELECT id, (name IS NULL) IS NULL FROM t_is_null_nested ORDER BY id
+PREHOOK: type: QUERY
+PREHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+POSTHOOK: query: SELECT id, (name IS NULL) IS NULL FROM t_is_null_nested ORDER BY id
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+1	false
+2	false
+PREHOOK: query: SELECT id, (name IS NOT NULL) IS NULL FROM t_is_null_nested ORDER BY id
+PREHOOK: type: QUERY
+PREHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+POSTHOOK: query: SELECT id, (name IS NOT NULL) IS NULL FROM t_is_null_nested ORDER BY id
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+1	false
+2	false
+PREHOOK: query: SELECT id, (name IS NULL) IS NOT NULL FROM t_is_null_nested ORDER BY id
+PREHOOK: type: QUERY
+PREHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+POSTHOOK: query: SELECT id, (name IS NULL) IS NOT NULL FROM t_is_null_nested ORDER BY id
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+1	true
+2	true
+PREHOOK: query: SELECT id, (name IS NOT NULL) IS NOT NULL FROM t_is_null_nested ORDER BY id
+PREHOOK: type: QUERY
+PREHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+POSTHOOK: query: SELECT id, (name IS NOT NULL) IS NOT NULL FROM t_is_null_nested ORDER BY id
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+1	true
+2	true
+PREHOOK: query: SELECT id FROM t_is_null_nested WHERE (name IS NULL) IS NOT NULL ORDER BY id
+PREHOOK: type: QUERY
+PREHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+POSTHOOK: query: SELECT id FROM t_is_null_nested WHERE (name IS NULL) IS NOT NULL ORDER BY id
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+1
+2
+PREHOOK: query: SELECT id FROM t_is_null_nested WHERE (name IS NULL) IS NULL ORDER BY id
+PREHOOK: type: QUERY
+PREHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####
+POSTHOOK: query: SELECT id FROM t_is_null_nested WHERE (name IS NULL) IS NULL ORDER BY id
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@t_is_null_nested
+#### A masked pattern was here ####