diff --git a/eeschema/sch_file_versions.h b/eeschema/sch_file_versions.h
index 642a91a1ab..2ad78c104d 100644
--- a/eeschema/sch_file_versions.h
+++ b/eeschema/sch_file_versions.h
@@ -134,4 +134,5 @@
 //#define SEXPR_SCHEMATIC_FILE_VERSION 20250922  // Schematic variants.
 //#define SEXPR_SCHEMATIC_FILE_VERSION 20251012  // Flat schematic hierarchy support
 //#define SEXPR_SCHEMATIC_FILE_VERSION 20251028  // Updated properties formatting (do_not_autoplace, show_name)
-#define SEXPR_SCHEMATIC_FILE_VERSION 20260101  // PCB variants
+//#define SEXPR_SCHEMATIC_FILE_VERSION 20260101  // PCB variants
+#define SEXPR_SCHEMATIC_FILE_VERSION 20260306  // Variant in_bom semantics corrected
diff --git a/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr.cpp b/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr.cpp
index ccf79b2da0..3611f408cc 100644
--- a/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr.cpp
+++ b/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr.cpp
@@ -927,7 +927,7 @@ void SCH_IO_KICAD_SEXPR::saveSymbol( SCH_SYMBOL* aSymbol, const SCHEMATIC& aSche
                             KICAD_FORMAT::FormatBool( m_out, "exclude_from_sim", variant.m_ExcludedFromSim );
 
                         if( variant.m_ExcludedFromBOM != aSymbol->GetExcludedFromBOM() )
-                            KICAD_FORMAT::FormatBool( m_out, "in_bom", variant.m_ExcludedFromBOM );
+                            KICAD_FORMAT::FormatBool( m_out, "in_bom", !variant.m_ExcludedFromBOM );
 
                         if( variant.m_ExcludedFromBoard != aSymbol->GetExcludedFromBoard() )
                             KICAD_FORMAT::FormatBool( m_out, "on_board", !variant.m_ExcludedFromBoard );
@@ -1180,7 +1180,7 @@ void SCH_IO_KICAD_SEXPR::saveSheet( SCH_SHEET* aSheet, const SCH_SHEET_LIST& aSh
                         KICAD_FORMAT::FormatBool( m_out, "exclude_from_sim", variant.m_ExcludedFromSim );
 
                     if( variant.m_ExcludedFromBOM != aSheet->GetExcludedFromBOM() )
-                        KICAD_FORMAT::FormatBool( m_out, "in_bom", variant.m_ExcludedFromBOM );
+                        KICAD_FORMAT::FormatBool( m_out, "in_bom", !variant.m_ExcludedFromBOM );
 
                     for( const auto&[fname, fvalue] : variant.m_Fields )
                     {
diff --git a/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr_parser.cpp b/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr_parser.cpp
index af328f0037..e1011bc34f 100644
--- a/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr_parser.cpp
+++ b/eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr_parser.cpp
@@ -3408,7 +3408,7 @@ SCH_SYMBOL* SCH_IO_KICAD_SEXPR_PARSER::parseSchematicSymbol()
                                     break;
 
                                 case T_in_bom:
-                                    variant.m_ExcludedFromBOM = parseBool();
+                                    variant.m_ExcludedFromBOM = ( m_requiredVersion >= 20260306 ) ^ parseBool();
                                     NeedRIGHT();
                                     break;
 
@@ -3872,7 +3872,7 @@ SCH_SHEET* SCH_IO_KICAD_SEXPR_PARSER::parseSheet()
                                     break;
 
                                 case T_in_bom:
-                                    variant.m_ExcludedFromBOM = parseBool();
+                                    variant.m_ExcludedFromBOM = ( m_requiredVersion >= 20260306 ) ^ parseBool();
                                     NeedRIGHT();
                                     break;