diff --git a/basic/qa/basic_coverage/test_ismissing_basic.bas b/basic/qa/basic_coverage/test_ismissing_basic.bas
index 0996da0f82a4..ee515c6c8540 100644
--- a/basic/qa/basic_coverage/test_ismissing_basic.bas
+++ b/basic/qa/basic_coverage/test_ismissing_basic.bas
@@ -109,6 +109,15 @@ Sub verify_testIsMissingBasic()
     TestUtil.AssertEqual(TestOptArrayByRefByVal(, aB), IsMissingA, "TestOptArrayByRefByVal(, B)")
     TestUtil.AssertEqual(TestOptArrayByRefByVal(aA, aB), IsMissingNone, "TestOptArrayByRefByVal(A, B)")
 
+    ' tdf#143706 - optionals with named arguments (:= syntax)
+    ' Without the fix in place, this test would have failed with:
+    ' - Expected: 0  (IsMissingA)
+    ' - Actual  : -1 (IsMissingNone)
+    TestUtil.AssertEqual(TestOptVariant(B := 456), IsMissingA, "TestOptVariant(B := 456)")
+    TestUtil.AssertEqual(TestOptVariant(A := 123), IsMissingB, "TestOptVariant(A := 123)")
+    TestUtil.AssertEqual(TestOptVariant(A := 123, B := 456), IsMissingNone, "TestOptVariant(A := 123, B := 456)")
+    TestUtil.AssertEqual(TestOptVariant(B := 456, A := 123), IsMissingNone, "TestOptVariant(B := 456, A := 123)")
+
     Exit Sub
 errorHandler:
     TestUtil.ReportErrorHandler("verify_testIsMissingBasic", Err, Error$, Erl)
diff --git a/basic/qa/basic_coverage/test_ismissing_compatible.bas b/basic/qa/basic_coverage/test_ismissing_compatible.bas
index 6d11ab0902be..792418b927b2 100644
--- a/basic/qa/basic_coverage/test_ismissing_compatible.bas
+++ b/basic/qa/basic_coverage/test_ismissing_compatible.bas
@@ -109,6 +109,15 @@ Sub verify_testIsMissingCompatible()
     TestUtil.AssertEqual(TestOptArrayByRefByVal(, aB), IsMissingA, "TestOptArrayByRefByVal(, B)")
     TestUtil.AssertEqual(TestOptArrayByRefByVal(aA, aB), IsMissingNone, "TestOptArrayByRefByVal(A, B)")
 
+    ' tdf#143706 - optionals with named arguments (:= syntax)
+    ' Without the fix in place, this test would have failed with:
+    ' - Expected: 0  (IsMissingA)
+    ' - Actual  : -1 (IsMissingNone)
+    TestUtil.AssertEqual(TestOptVariant(B := 456), IsMissingA, "TestOptVariant(B := 456)")
+    TestUtil.AssertEqual(TestOptVariant(A := 123), IsMissingNone, "TestOptVariant(A := 123)")
+    TestUtil.AssertEqual(TestOptVariant(A := 123, B := 456), IsMissingNone, "TestOptVariant(A := 123, B := 456)")
+    TestUtil.AssertEqual(TestOptVariant(B := 456, A := 123), IsMissingNone, "TestOptVariant(B := 456, A := 123)")
+
     Exit Sub
 errorHandler:
     TestUtil.ReportErrorHandler("verify_testIsMissingCompatible", Err, Error$, Erl)
diff --git a/basic/qa/vba_tests/ismissing.vb b/basic/qa/vba_tests/ismissing.vb
index febe0339f68a..3d32b8db6861 100644
--- a/basic/qa/vba_tests/ismissing.vb
+++ b/basic/qa/vba_tests/ismissing.vb
@@ -115,6 +115,15 @@ Sub verify_testIsMissingVba()
     ' TestUtil.AssertEqual(TestOptArrayByRefByVal(, aB), IsMissingA, "TestOptArrayByRefByVal(, B)")
     TestUtil.AssertEqual(TestOptArrayByRefByVal(aA, aB), IsMissingNone, "TestOptArrayByRefByVal(A, B)")
 
+    ' tdf#143706 - optionals with named arguments (:= syntax)
+    ' Without the fix in place, this test would have failed with:
+    ' - Expected: 0  (IsMissingA)
+    ' - Actual  : -1 (IsMissingNone)
+    TestUtil.AssertEqual(TestOptVariant(B := 456), IsMissingA, "TestOptVariant(B := 456)")
+    TestUtil.AssertEqual(TestOptVariant(A := 123), IsMissingNone, "TestOptVariant(A := 123)")
+    TestUtil.AssertEqual(TestOptVariant(A := 123, B := 456), IsMissingNone, "TestOptVariant(A := 123, B := 456)")
+    TestUtil.AssertEqual(TestOptVariant(B := 456, A := 123), IsMissingNone, "TestOptVariant(B := 456, A := 123)")
+
     Exit Sub
 errorHandler:
     TestUtil.ReportErrorHandler("verify_testIsMissingVba", Err, Error$, Erl)
diff --git a/basic/source/runtime/runtime.cxx b/basic/source/runtime/runtime.cxx
index b625b928bc2d..40d5eebe7b6b 100644
--- a/basic/source/runtime/runtime.cxx
+++ b/basic/source/runtime/runtime.cxx
@@ -3923,6 +3923,27 @@ void SbiRuntime::SetupArgs( SbxVariable* p, sal_uInt32 nOp1 )
                     }
                     pArg->Put(pVar, nCurPar++);
                 }
+                // tdf#143706 - mark skipped named optional parameters as missing/empty
+                SbxMethod* pSbxMeth = dynamic_cast<SbxMethod*>(p);
+                const bool bIsRuntimeFunction = pSbxMeth && pSbxMeth->IsRuntimeFunction();
+                for (sal_uInt32 j = 1; j < pArg->Count(); j++)
+                {
+                    if (!pArg->GetRef(j))
+                    {
+                        SbxVariableRef xVar;
+                        if (bIsRuntimeFunction)
+                            xVar = new SbxVariable(SbxEMPTY);
+                        else
+                        {
+                            // Same as in SbiRuntime::StepEMPTY(), because the compiler does not
+                            // generate a StepEMPTY for StepPARAM when there is no COMMA token
+                            xVar = new SbxVariable(SbxVARIANT);
+                            xVar->PutErr(448);
+                            SetIsMissing(xVar.get());
+                        }
+                        pArg->Put(xVar.get(), j);
+                    }
+                }
                 refArgv = pArg;
             }
         }