diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3053,6 +3053,10 @@
     if (Left.is(TT_CSharpNullConditionalLSquare))
       return Style.SpacesInSquareBrackets;
 
+    // space after var in `var (key, value)`
+    if (Left.is(Keywords.kw_var) && Right.is(tok::l_paren))
+      return true;
+
     // space between keywords and paren e.g. "using ("
     if (Right.is(tok::l_paren))
       if (Left.isOneOf(tok::kw_using, Keywords.kw_async, Keywords.kw_when))
diff --git a/clang/unittests/Format/FormatTestCSharp.cpp b/clang/unittests/Format/FormatTestCSharp.cpp
--- a/clang/unittests/Format/FormatTestCSharp.cpp
+++ b/clang/unittests/Format/FormatTestCSharp.cpp
@@ -698,6 +698,7 @@
   verifyFormat(R"(Result this[Index x] => Foo(x);)", Style);
 
   verifyFormat(R"(char[,,] rawCharArray = MakeCharacterGrid();)", Style);
+  verifyFormat(R"(var (key, value))", Style);
 
   // Not seen as a C-style cast.
   verifyFormat(R"(//