diff --git a/Control/AthenaConfiguration/python/TestDefaults.py b/Control/AthenaConfiguration/python/TestDefaults.py
index b60e12c05331d5486031555be3d9e1f2e2affecc..062c03e7ef2222a58bc25a7c7b12ad30edec190d 100644
--- a/Control/AthenaConfiguration/python/TestDefaults.py
+++ b/Control/AthenaConfiguration/python/TestDefaults.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
+# Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
 # Files for use in configuration unit tests
 
 class defaultTestFiles:
@@ -65,7 +65,7 @@ class defaultGeometryTags:
 
 class defaultConditionsTags:
     RUN2_DATA = "CONDBR2-BLKPA-RUN2-11"
-    RUN2_MC = "OFLCOND-MC16-SDR-RUN2-11"
+    RUN2_MC = "OFLCOND-MC16-SDR-RUN2-12"
     RUN3_DATA = "CONDBR2-BLKPA-2024-04"  # TODO: switch to proper global tag once available
     RUN3_MC = "OFLCOND-MC23-SDR-RUN3-05"
     RUN4_MC = "OFLCOND-MC21-SDR-RUN4-02"
diff --git a/Simulation/Overlay/OverlayConfiguration/python/OverlayTestHelpers.py b/Simulation/Overlay/OverlayConfiguration/python/OverlayTestHelpers.py
index 0e5bf24875cc744d4841c8dfbd87547a19f62174..e65b14fdf0bc47559bef24c1929aaf5b54041bb9 100644
--- a/Simulation/Overlay/OverlayConfiguration/python/OverlayTestHelpers.py
+++ b/Simulation/Overlay/OverlayConfiguration/python/OverlayTestHelpers.py
@@ -50,7 +50,7 @@ def overlayTestFlags(flags, args):
     if args.disableTruth:
         flags.Digitization.EnableTruth = False
 
-    from AthenaConfiguration.TestDefaults import defaultTestFiles
+    from AthenaConfiguration.TestDefaults import defaultTestFiles, defaultConditionsTags
     from AthenaConfiguration.Enums import ProductionStep
     flags.Common.ProductionStep = ProductionStep.Overlay
     if args.data:
@@ -58,7 +58,7 @@ def overlayTestFlags(flags, args):
         flags.Input.Files = defaultTestFiles.HITS_DATA_OVERLAY
         flags.Input.SecondaryFiles = defaultTestFiles.RAW_BKG
         flags.Output.RDOFileName = "dataOverlayRDO.pool.root"
-        flags.IOVDb.GlobalTag = "CONDBR2-BLKPA-RUN2-10"
+        flags.IOVDb.GlobalTag = defaultConditionsTags.RUN2_DATA
         flags.IOVDb.DatabaseInstance = "CONDBR2"
         flags.Overlay.DataOverlay = True
         from Campaigns import DataOverlayPPTest
@@ -68,19 +68,19 @@ def overlayTestFlags(flags, args):
         if args.run is LHCPeriod.Run2:
             flags.Input.Files = defaultTestFiles.RDO_BKG_RUN2
             flags.Input.SecondaryFiles = defaultTestFiles.HITS_RUN2
-            flags.IOVDb.GlobalTag = "OFLCOND-MC16-SDR-RUN2-12"
+            flags.IOVDb.GlobalTag = defaultConditionsTags.RUN2_MC
             from Campaigns import MC20e
             MC20e(flags)
         elif args.run is LHCPeriod.Run3:
             flags.Input.Files = defaultTestFiles.RDO_BKG_RUN3
             flags.Input.SecondaryFiles = defaultTestFiles.HITS_RUN3
-            flags.IOVDb.GlobalTag = "OFLCOND-MC21-SDR-RUN3-09"
+            flags.IOVDb.GlobalTag = defaultConditionsTags.RUN3_MC
             from Campaigns import MC21a
             MC21a(flags)
         elif args.run is LHCPeriod.Run4:
             flags.Input.Files = defaultTestFiles.RDO_BKG_RUN4
             flags.Input.SecondaryFiles = defaultTestFiles.HITS_RUN4
-            flags.IOVDb.GlobalTag = "OFLCOND-MC21-SDR-RUN4-01"
+            flags.IOVDb.GlobalTag = defaultConditionsTags.RUN4_MC
             from Campaigns import PhaseIIPileUp200
             PhaseIIPileUp200(flags)
         else: