diff --git a/experiments/ClimaEarth/run_amip.jl b/experiments/ClimaEarth/run_amip.jl
index 44df091767..7f8d57d303 100644
--- a/experiments/ClimaEarth/run_amip.jl
+++ b/experiments/ClimaEarth/run_amip.jl
@@ -532,7 +532,7 @@ checkpoint_cb = CallbackManager.HourlyCallback(
 ) # 20 days
 update_firstdayofmonth!_cb = CallbackManager.MonthlyCallback(
     dt = FT(1),
-    func = CallbackManager.update_firstdayofmonth!,
+    func = Interfacer.update_firstdayofmonth!,
     ref_date = [dates.first_day_of_month[1]],
     active = true,
 )
diff --git a/experiments/ClimaEarth/run_cloudless_aquaplanet.jl b/experiments/ClimaEarth/run_cloudless_aquaplanet.jl
index 87c4d11657..15ea762c3d 100644
--- a/experiments/ClimaEarth/run_cloudless_aquaplanet.jl
+++ b/experiments/ClimaEarth/run_cloudless_aquaplanet.jl
@@ -225,7 +225,7 @@ checkpoint_cb = CallbackManager.HourlyCallback(
 ) # 20 days
 update_firstdayofmonth!_cb = CallbackManager.MonthlyCallback(
     dt = FT(1),
-    func = CallbackManager.update_firstdayofmonth!,
+    func = Interfacer.update_firstdayofmonth!,
     ref_date = [dates.first_day_of_month[1]],
     active = true,
 )
diff --git a/experiments/ClimaEarth/run_cloudy_aquaplanet.jl b/experiments/ClimaEarth/run_cloudy_aquaplanet.jl
index dede5363c8..3c3997d9b2 100644
--- a/experiments/ClimaEarth/run_cloudy_aquaplanet.jl
+++ b/experiments/ClimaEarth/run_cloudy_aquaplanet.jl
@@ -246,7 +246,7 @@ checkpoint_cb = CallbackManager.HourlyCallback(
 ) # 20 days
 update_firstdayofmonth!_cb = CallbackManager.MonthlyCallback(
     dt = FT(1),
-    func = CallbackManager.update_firstdayofmonth!,
+    func = Interfacer.update_firstdayofmonth!,
     ref_date = [dates.first_day_of_month[1]],
     active = true,
 )
diff --git a/experiments/ClimaEarth/run_cloudy_slabplanet.jl b/experiments/ClimaEarth/run_cloudy_slabplanet.jl
index 7b909b6ae6..4eb11a506e 100644
--- a/experiments/ClimaEarth/run_cloudy_slabplanet.jl
+++ b/experiments/ClimaEarth/run_cloudy_slabplanet.jl
@@ -292,7 +292,7 @@ checkpoint_cb = CallbackManager.HourlyCallback(
 ) # 20 days
 update_firstdayofmonth!_cb = CallbackManager.MonthlyCallback(
     dt = FT(1),
-    func = CallbackManager.update_firstdayofmonth!,
+    func = Interfacer.update_firstdayofmonth!,
     ref_date = [dates.first_day_of_month[1]],
     active = true,
 )
diff --git a/experiments/ClimaEarth/run_dry_held_suarez.jl b/experiments/ClimaEarth/run_dry_held_suarez.jl
index 1477bc27dc..c2860fc153 100644
--- a/experiments/ClimaEarth/run_dry_held_suarez.jl
+++ b/experiments/ClimaEarth/run_dry_held_suarez.jl
@@ -187,7 +187,7 @@ checkpoint_cb = CallbackManager.HourlyCallback(
 ) # 20 days TODO: not GPU friendly
 update_firstdayofmonth!_cb = CallbackManager.MonthlyCallback(
     dt = FT(1),
-    func = CallbackManager.update_firstdayofmonth!,
+    func = Interfacer.update_firstdayofmonth!,
     ref_date = [dates.first_day_of_month[1]],
     active = true,
 )
diff --git a/experiments/ClimaEarth/run_moist_held_suarez.jl b/experiments/ClimaEarth/run_moist_held_suarez.jl
index e2f1bdf8c2..9eb735937e 100644
--- a/experiments/ClimaEarth/run_moist_held_suarez.jl
+++ b/experiments/ClimaEarth/run_moist_held_suarez.jl
@@ -232,7 +232,7 @@ checkpoint_cb = CallbackManager.HourlyCallback(
 )
 update_firstdayofmonth!_cb = CallbackManager.MonthlyCallback(
     dt = FT(1),
-    func = CallbackManager.update_firstdayofmonth!,
+    func = Interfacer.update_firstdayofmonth!,
     ref_date = [dates.first_day_of_month[1]],
     active = true,
 )
diff --git a/src/Interfacer.jl b/src/Interfacer.jl
index 0d995a38a4..ae10268839 100644
--- a/src/Interfacer.jl
+++ b/src/Interfacer.jl
@@ -96,6 +96,16 @@ Return the model date at the current timestep.
 """
 current_date(cs::CoupledSimulation, t) = cs.dates.date0[1] + Dates.Second(t)
 
+"""
+    update_firstdayofmonth!(cs::Interfacer.CoupledSimulation, _)
+
+This function updates the first of the month reference date.
+"""
+function update_firstdayofmonth!(cs, _)
+    cs.dates.first_day_of_month[1] = cs.dates.first_day_of_month[1] + Dates.Month(1)
+    @info("update_firstdayofmonth! at $(cs.dates.date)")
+end
+
 """
     ComponentModelSimulation