diff --git a/flang/include/flang/Optimizer/Dialect/FIRType.h b/flang/include/flang/Optimizer/Dialect/FIRType.h
--- a/flang/include/flang/Optimizer/Dialect/FIRType.h
+++ b/flang/include/flang/Optimizer/Dialect/FIRType.h
@@ -24,6 +24,26 @@
 using KindTy = unsigned;
 } // namespace fir
 
+//===----------------------------------------------------------------------===//
+// BaseBoxType
+//===----------------------------------------------------------------------===//
+
+namespace fir {
+
+/// This class provides a shared interface for box and class types.
+class BaseBoxType : public mlir::Type {
+public:
+  using mlir::Type::Type;
+
+  /// Returns the element type of this box type.
+  mlir::Type getEleTy() const;
+
+  /// Methods for support type inquiry through isa, cast, and dyn_cast.
+  static bool classof(mlir::Type type);
+};
+
+} // namespace fir
+
 #define GET_TYPEDEF_CLASSES
 #include "flang/Optimizer/Dialect/FIROpsTypes.h.inc"
 
@@ -283,6 +303,10 @@
 mlir::Type fromRealTypeID(mlir::MLIRContext *context, llvm::Type::TypeID typeID,
                           fir::KindTy kind);
 
+inline bool BaseBoxType::classof(mlir::Type type) {
+  return type.isa<fir::BoxType>();
+}
+
 } // namespace fir
 
 #endif // FORTRAN_OPTIMIZER_DIALECT_FIRTYPE_H
diff --git a/flang/include/flang/Optimizer/Dialect/FIRTypes.td b/flang/include/flang/Optimizer/Dialect/FIRTypes.td
--- a/flang/include/flang/Optimizer/Dialect/FIRTypes.td
+++ b/flang/include/flang/Optimizer/Dialect/FIRTypes.td
@@ -20,7 +20,9 @@
 // FIR Types
 //===----------------------------------------------------------------------===//
 
-class FIR_Type<string name, string typeMnemonic> : TypeDef<fir_Dialect, name> {
+class FIR_Type<string name, string typeMnemonic, list<Trait> traits = [],
+               string baseCppClass = "::mlir::Type">
+    : TypeDef<fir_Dialect, name, traits, baseCppClass> {
   let mnemonic = typeMnemonic;
 }
 
@@ -66,7 +68,7 @@
   let hasCustomAssemblyFormat = 1;
 }
 
-def fir_BoxType : FIR_Type<"Box", "box"> {
+def fir_BoxType : FIR_Type<"Box", "box", [], "BaseBoxType"> {
   let summary = "The type of a Fortran descriptor";
 
   let description = [{
diff --git a/flang/lib/Optimizer/Dialect/FIRType.cpp b/flang/lib/Optimizer/Dialect/FIRType.cpp
--- a/flang/lib/Optimizer/Dialect/FIRType.cpp
+++ b/flang/lib/Optimizer/Dialect/FIRType.cpp
@@ -924,6 +924,15 @@
   }
 }
 
+//===----------------------------------------------------------------------===//
+// BaseBoxType
+//===----------------------------------------------------------------------===//
+
+mlir::Type BaseBoxType::getEleTy() const {
+  return llvm::TypeSwitch<fir::BaseBoxType, mlir::Type>(*this)
+      .Case<fir::BoxType>([](auto type) { return type.getEleTy(); });
+}
+
 //===----------------------------------------------------------------------===//
 // FIROpsDialect
 //===----------------------------------------------------------------------===//