diff --git a/stackit/internal/services/postgresflexalpha/utils/planModifiers.go b/stackit/internal/utils/planModifiers.go
similarity index 100%
rename from stackit/internal/services/postgresflexalpha/utils/planModifiers.go
rename to stackit/internal/utils/planModifiers.go
diff --git a/stackit/internal/utils/planModifiers_test.go b/stackit/internal/utils/planModifiers_test.go
new file mode 100644
index 00000000..337ea36f
--- /dev/null
+++ b/stackit/internal/utils/planModifiers_test.go
@@ -0,0 +1,224 @@
+package utils
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/hashicorp/terraform-plugin-framework/resource/schema"
+	"github.com/hashicorp/terraform-plugin-framework/types"
+	"github.com/stackitcloud/stackit-sdk-go/core/utils"
+)
+
+func TestReadModifiersConfig(t *testing.T) {
+	testcases := []struct {
+		name    string
+		content []byte
+		wantErr bool
+	}{
+		{
+			name: "valid yaml",
+			content: []byte(`
+fields:
+  - name: 'id'
+    modifiers:
+      - 'UseStateForUnknown'
+`),
+			wantErr: false,
+		},
+		{
+			name:    "invalid yaml",
+			content: []byte(`invalid: yaml: :`),
+			wantErr: true,
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(
+			tc.name, func(t *testing.T) {
+				_, err := ReadModifiersConfig(tc.content)
+				if (err != nil) != tc.wantErr {
+					t.Errorf("ReadModifiersConfig() error = %v, wantErr %v", err, tc.wantErr)
+				}
+			},
+		)
+	}
+}
+
+func TestAddPlanModifiersToResourceSchema(t *testing.T) {
+	testcases := []struct {
+		name    string
+		fields  *Fields
+		sch     *schema.Schema
+		wantErr bool
+	}{
+		{
+			name: "full coverage - all types and nested structures",
+			fields: &Fields{
+				Fields: []*Field{
+					{
+						Name:      "string_attr",
+						Modifiers: []*string{utils.Ptr("RequiresReplace"), utils.Ptr("UseStateForUnknown")},
+					},
+					{Name: "bool_attr", Modifiers: []*string{utils.Ptr("RequiresReplace")}},
+					{Name: "int_attr", Modifiers: []*string{utils.Ptr("UseStateForUnknown")}},
+					{Name: "list_attr", Modifiers: []*string{utils.Ptr("RequiresReplace")}},
+					{Name: "Nested.sub_string", Modifiers: []*string{utils.Ptr("RequiresReplace")}},
+				},
+			},
+			sch: &schema.Schema{
+				Attributes: map[string]schema.Attribute{
+					"StringAttr": schema.StringAttribute{},
+					"BoolAttr":   schema.BoolAttribute{},
+					"IntAttr":    schema.Int64Attribute{},
+					"ListAttr":   schema.ListAttribute{},
+					"Nested": schema.SingleNestedAttribute{
+						Attributes: map[string]schema.Attribute{
+							"SubString": schema.StringAttribute{},
+						},
+					},
+					"Unsupported": schema.MapAttribute{ElementType: types.StringType}, // Triggers default/warn case
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "validation error - invalid modifier",
+			fields: &Fields{
+				Fields: []*Field{
+					{Name: "id", Modifiers: []*string{utils.Ptr("InvalidModifier")}},
+				},
+			},
+			sch: &schema.Schema{
+				Attributes: map[string]schema.Attribute{"id": schema.StringAttribute{}},
+			},
+			wantErr: true,
+		},
+		{
+			name: "validation error - empty modifier",
+			fields: &Fields{
+				Fields: []*Field{
+					{Name: "id", Modifiers: []*string{utils.Ptr("")}},
+				},
+			},
+			sch:     &schema.Schema{},
+			wantErr: true,
+		},
+		{
+			name:    "nil fields - should return nil",
+			fields:  nil,
+			sch:     &schema.Schema{},
+			wantErr: false,
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(
+			tc.name, func(t *testing.T) {
+				err := AddPlanModifiersToResourceSchema(tc.fields, tc.sch)
+
+				if (err != nil) != tc.wantErr {
+					t.Fatalf("AddPlanModifiersToResourceSchema() error = %v, wantErr %v", err, tc.wantErr)
+				}
+
+				if !tc.wantErr && tc.name == "full coverage - all types and nested structures" {
+					// Check StringAttr
+					if sAttr, ok := tc.sch.Attributes["StringAttr"].(schema.StringAttribute); ok {
+						if len(sAttr.PlanModifiers) != 2 {
+							t.Errorf("StringAttr: expected 2 modifiers, got %d", len(sAttr.PlanModifiers))
+						}
+					}
+
+					// Check Nested Sub-Attribute
+					if nested, ok := tc.sch.Attributes["Nested"].(schema.SingleNestedAttribute); ok {
+						if subAttr, ok := nested.Attributes["SubString"].(schema.StringAttribute); ok {
+							if len(subAttr.PlanModifiers) != 1 {
+								// Dies schlug vorher fehl, weil der Prefix "Nested" statt "nested" war
+								t.Errorf("Nested SubString: expected 1 modifier, got %d", len(subAttr.PlanModifiers))
+							}
+						} else {
+							t.Error("SubString attribute not found in Nested")
+						}
+					} else {
+						t.Error("Nested attribute not found")
+					}
+				}
+			},
+		)
+	}
+}
+
+func TestFieldListToMap(t *testing.T) {
+	testcases := []struct {
+		name   string
+		fields *Fields
+		want   map[string][]*string
+	}{
+		{
+			name: "convert list to map",
+			fields: &Fields{
+				Fields: []*Field{
+					{Name: "test", Modifiers: []*string{utils.Ptr("mod")}},
+				},
+			},
+			want: map[string][]*string{
+				"test": {utils.Ptr("mod")},
+			},
+		},
+		{
+			name:   "nil fields",
+			fields: nil,
+			want:   map[string][]*string{},
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(
+			tc.name, func(t *testing.T) {
+				got := fieldListToMap(tc.fields)
+				if diff := cmp.Diff(tc.want, got); diff != "" {
+					t.Errorf("fieldListToMap() mismatch (-want +got):\n%s", diff)
+				}
+			},
+		)
+	}
+}
+
+func TestHandleTypeMismatches(t *testing.T) {
+	modifiers := []*string{utils.Ptr("RequiresReplace")}
+
+	t.Run(
+		"bool type mismatch", func(t *testing.T) {
+			_, err := handleBoolPlanModifiers(schema.StringAttribute{}, modifiers)
+			if err == nil {
+				t.Error("expected error for type mismatch in handleBoolPlanModifiers")
+			}
+		},
+	)
+
+	t.Run(
+		"string type mismatch", func(t *testing.T) {
+			_, err := handleStringPlanModifiers(schema.BoolAttribute{}, modifiers)
+			if err == nil {
+				t.Error("expected error for type mismatch in handleStringPlanModifiers")
+			}
+		},
+	)
+
+	t.Run(
+		"int64 type mismatch", func(t *testing.T) {
+			_, err := handleInt64PlanModifiers(schema.StringAttribute{}, modifiers)
+			if err == nil {
+				t.Error("expected error for type mismatch in handleInt64PlanModifiers")
+			}
+		},
+	)
+
+	t.Run(
+		"list type mismatch", func(t *testing.T) {
+			_, err := handleListPlanModifiers(schema.StringAttribute{}, modifiers)
+			if err == nil {
+				t.Error("expected error for type mismatch in handleListPlanModifiers")
+			}
+		},
+	)
+}