diff --git a/calcdatelib/calcdatelib.go b/calcdatelib/calcdatelib.go
index 8871896..d18d019 100644
--- a/calcdatelib/calcdatelib.go
+++ b/calcdatelib/calcdatelib.go
@@ -311,6 +311,28 @@ func (d *Date) SetEndDate() *Date {
 	return d
 }
 
+func (d *Date) SetEndMonth() *Date {
+	d.second = 59
+	d.minute = 59
+	d.hour = 23
+	if d.month == 0 {
+		d.month = 12
+	}
+	d.day = DayInMonth(d.year, d.month)
+	return d
+}
+
+func (d *Date) SetBeginMonth() *Date {
+	d.second = 0
+	d.minute = 0
+	d.hour = 0
+	d.day = 1
+	if d.month == 0 {
+		d.month = 1
+	}
+	return d
+}
+
 func GetInterval(d1 *Date, d2 *Date) time.Duration {
 	diff := d1.Time().Sub(d2.Time())
 	if diff > 0 {
diff --git a/calcdatelib/calcdatelib_test.go b/calcdatelib/calcdatelib_test.go
index 9130653..e26bb17 100644
--- a/calcdatelib/calcdatelib_test.go
+++ b/calcdatelib/calcdatelib_test.go
@@ -394,3 +394,79 @@ func TestGetInterval(t *testing.T) {
 		})
 	}
 }
+
+func TestDate_SetEndMonth(t *testing.T) {
+	tests := []struct {
+		name string
+		date string
+		want time.Time
+	}{
+		{
+			name: "end of february",
+			date: "2022/02/05 01:02:03",
+			want: time.Date(2022, 2, 28, 23, 59, 59, 0, time.UTC),
+		},
+		{
+			name: "end of february",
+			date: "2022/02/05 ::",
+			want: time.Date(2022, 2, 28, 23, 59, 59, 0, time.UTC),
+		},
+		{
+			name: "end of december",
+			date: "2022/12/05 01:02:03",
+			want: time.Date(2022, 12, 31, 23, 59, 59, 0, time.UTC),
+		},
+		{
+			name: "end of january",
+			date: "2022/01/05 01:02:03",
+			want: time.Date(2022, 1, 31, 23, 59, 59, 0, time.UTC),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			d, _ := NewDate(tt.date, "%YYYY/%MM/%DD %hh:%mm:%ss", "UTC")
+			result := d.SetEndMonth().Time()
+			if result != tt.want {
+				t.Errorf("Date.SetEndMonth() = %v, want %v", result, tt.want)
+			}
+		})
+	}
+}
+
+func TestDate_SetBeginMonth(t *testing.T) {
+	tests := []struct {
+		name string
+		date string
+		want time.Time
+	}{
+		{
+			name: "begin of february",
+			date: "2022/02/05 01:02:03",
+			want: time.Date(2022, 2, 1, 0, 0, 0, 0, time.UTC),
+		},
+		{
+			name: "begin of december",
+			date: "2022/12/05 01:02:03",
+			want: time.Date(2022, 12, 1, 0, 0, 0, 0, time.UTC),
+		},
+		{
+			name: "begin of january",
+			date: "2022/01/05 01:02:03",
+			want: time.Date(2022, 1, 1, 0, 0, 0, 0, time.UTC),
+		},
+		{
+			name: "begin of january",
+			date: "2022/01/05 ::",
+			want: time.Date(2022, 1, 1, 0, 0, 0, 0, time.UTC),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			d, _ := NewDate(tt.date, "%YYYY/%MM/%DD %hh:%mm:%ss", "UTC")
+			result := d.SetBeginMonth().Time()
+			if result != tt.want {
+				t.Errorf("Date.SetBeginMonth() = %v, want %v", result, tt.want)
+			}
+		})
+	}
+}