diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2562f3d..67d1e10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
 ## Changelog
 All notable changes to this project will be documented in this file. <br/>
-The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/). This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
\ No newline at end of file
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/). This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## 0.2.2-Beta 
+- Added a new feature to display old transaction history by CLI
+  e.g. `etracker --month 10 --year 2023`
+- Added `--interval` option to get the transaction data for a specific interval and unit seconds
+  e.g. `etracker --interval 10` # Every 10 seconds
\ No newline at end of file
diff --git a/README.md b/README.md
index 1bbc299..95c6f05 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,8 @@ transactions and summarizing them in daily, monthly, and yearly reports.
 - **Database Storage**: Store transaction data in an SQLite database with indexing for faster queries.
 - **Reporting**:
   - Daily, monthly, and yearly transaction summaries.
+  - Can generate previous month transaction data.
+  - Can add `--interval` option to get the transaction data for a specific interval.
   - Total expense calculation per category.
 - **Display**: Generate reports in a tabular format using the `tabulate` library.
 - **Environment Variables**: Securely configure sensitive data like email credentials and target subjects.
@@ -32,6 +34,7 @@ ExpenseTracker/
    ├── logs_config.py        # Logging configuration
    ├── display.py            # Handles data display
    ├── gmail_authenticator.py # Gmail OAuth authentication
+   ├── validators.py         # Validates user's input
 ├── tests/                # Unit tests for the application
    │   ├── __init__.py
    │   ├── test_db.py
@@ -39,7 +42,8 @@ ExpenseTracker/
    │   ├── test_email_fetcher.py
    │   ├── test_email_parser.py
    │   ├── test_etd.py
-   │   └── test_tracker.py
+   │   └── test_tracker.py.
+   │   └── test_validators.py.
    │   
 └── README.md             # Project documentation
 ```
diff --git a/tests/test_validators.py b/tests/test_validators.py
new file mode 100644
index 0000000..d3cda24
--- /dev/null
+++ b/tests/test_validators.py
@@ -0,0 +1,112 @@
+import unittest
+from tracker.validators import validate_month_year, validate_args, validate_sender_email
+
+
+class TestValidateSenderEmail(unittest.TestCase):
+    def test_valid_sender_email(self):
+        class DummyClass:
+            sender_email = "test@example.com"
+
+        @validate_sender_email
+        def dummy_function(obj):
+            return "Function executed"
+
+        instance = DummyClass()
+        self.assertEqual(dummy_function(instance), "Function executed")
+
+    def test_missing_sender_email_attribute(self):
+        class DummyClass:
+            pass
+
+        @validate_sender_email
+        def dummy_function(obj):
+            return "Function executed"
+
+        instance = DummyClass()
+        with self.assertRaises(ValueError) as context:
+            dummy_function(instance)
+        self.assertEqual(str(context.exception), "Missing environment variable: ET_SENDER_EMAIL")
+
+    def test_empty_sender_email(self):
+        class DummyClass:
+            sender_email = ""
+
+        @validate_sender_email
+        def dummy_function(obj):
+            return "Function executed"
+
+        instance = DummyClass()
+        with self.assertRaises(ValueError) as context:
+            dummy_function(instance)
+        self.assertEqual(str(context.exception), "Missing environment variable: ET_SENDER_EMAIL")
+
+    def test_invalid_first_argument(self):
+        @validate_sender_email
+        def dummy_function():
+            return "Function executed"
+
+        with self.assertRaises(ValueError) as context:
+            dummy_function()
+
+        self.assertEqual(str(context.exception), "First argument must be an instance of the class.")
+
+
+class TestValidateMonthYear(unittest.TestCase):
+    def test_validate_month_year_valid_inputs(self):
+        @validate_month_year
+        def dummy_function(self, month, year):
+            return f"Month: {month}, Year: {year}"
+
+        self.assertEqual(dummy_function(self, 1, 2023), "Month: 1, Year: 2023")
+        self.assertEqual(dummy_function(self,"January", 2023), "Month: January, Year: 2023")
+
+    def test_validate_month_year_invalid_year(self):
+        @validate_month_year
+        def dummy_function(self,month, year):
+            return f"Month: {month}, Year: {year}"
+
+        with self.assertRaises(ValueError) as context:
+            dummy_function(self, 1, 23)
+        self.assertEqual(str(context.exception), "Invalid year format: '23'. Year must be a 4-digit string.")
+
+    def test_validate_month_year_invalid_month(self):
+        @validate_month_year
+        def dummy_function(self, month, year):
+            return f"Month: {month}, Year: {year}"
+
+        with self.assertRaises(ValueError) as context:
+            dummy_function(self, 13, 2023)
+        self.assertEqual(str(context.exception), "Invalid month: '13'. Must be '01'-'12' or full month name.")
+
+        with self.assertRaises(ValueError) as context:
+            dummy_function(self,"InvalidMonth", 2023)
+        self.assertEqual(str(context.exception), "Invalid month: 'InvalidMonth'. Must be '01'-'12' or full month name.")
+
+    def test_validate_month_year_invalid_month_type(self):
+        @validate_month_year
+        def dummy_function(self, month, year):
+            return f"Month: {month}, Year: {year}"
+
+        with self.assertRaises(ValueError) as context:
+            dummy_function(self,[], 2023)
+        self.assertEqual(str(context.exception), "Month must be a string. Got <class 'list'> instead.")
+
+
+class TestValidateArgs(unittest.TestCase):
+    def test_validate_args_with_interval(self):
+        args = {"interval": True}
+        self.assertEqual(validate_args(args), ("continuous", None))
+
+    def test_validate_args_with_month_and_year(self):
+        args = {"month": "January", "year": "2023"}
+        self.assertEqual(validate_args(args), ("monthly", None))
+
+    def test_validate_args_with_interval_and_month(self):
+        args = {"interval": True, "month": "January"}
+        self.assertEqual(validate_args(args), ("error", "Cannot use --interval with --month/--year together."))
+
+    def test_validate_args_with_no_valid_combination(self):
+        args = {}
+        self.assertEqual(validate_args(args), ("continuous", None))
+
+
diff --git a/tracker/__version__.py b/tracker/__version__.py
index 767a002..b9314d5 100644
--- a/tracker/__version__.py
+++ b/tracker/__version__.py
@@ -1,4 +1,4 @@
 """
 Expense Tracker version
 """
-__version__ = "0.1.1-Beta"
+__version__ = "0.2.2-Beta"
diff --git a/tracker/expense_tracker.py b/tracker/expense_tracker.py
index 9bf5073..c51e645 100644
--- a/tracker/expense_tracker.py
+++ b/tracker/expense_tracker.py
@@ -1,7 +1,9 @@
+import argparse
 import datetime
 import os
 import time
 
+from tracker.validators import validate_month_year, validate_args, validate_sender_email
 from tracker.logs_config import logger
 from tracker.gmail_authenticator import GmailAuthenticator
 from tracker.email_fetcher import EmailFetcher
@@ -33,13 +35,12 @@ def __init__(self):
         self.sender_email = os.getenv("ET_SENDER_EMAIL")
         self.target_subjects = os.getenv("ET_TARGET_SUBJECTS", DEFAULT_SUBJECTS).split(",")
 
-        self.validate_env_variables()
-
     def validate_env_variables(self):
         if not self.sender_email:
             logger.error("Missing ET_SENDER_EMAIL. Please set this environment variable.")
             raise ValueError("Missing environment variable: ET_SENDER_EMAIL")
 
+    @validate_sender_email
     def run(self):
         try:
             messages = self.email_fetcher.filter_unread_messages(self.sender_email, self.target_subjects)
@@ -49,8 +50,8 @@ def run(self):
                 return
 
             for message in messages:
-                parser = EmailParser(message=message)
-                data = parser.extract_tags_values_from_body()
+                email_parser = EmailParser(message=message)
+                data = email_parser.extract_tags_values_from_body()
 
                 if self.process_data(data):
                     self.email_fetcher.mark_message_as_read(message.get("id"))
@@ -74,19 +75,50 @@ def show(self):
         res = self.db.generate_monthly_report(now.year, now.month)
         self.display.display_summary(res)
 
+    @validate_month_year
+    def get_monthly_summary(self, month, year) -> None:
+        self.display.display_summary(self.db.generate_monthly_report(year, month))
+
     def close(self):
         self.db.close_connection()
 
 
-if __name__ == '__main__':
+def run_continuous(interval: int = 3600):
     expense = ExpenseTracker()
     try:
         while True:
             expense.show()
             expense.run()
-            time.sleep(3600)  # An hour
-            expense.show() # Show the summary again
+            time.sleep(interval)  # An hour
+            expense.show()  # Show the summary again
     except KeyboardInterrupt:
         logger.info("Process interrupted. Exiting...")
     finally:
         expense.close()
+
+
+def run_monthly_summary(month, year):
+    expense = ExpenseTracker()
+    try:
+        expense.get_monthly_summary(month, year)
+    except Exception as err:
+        logger.error(f"Error generating summary: {err}")
+    finally:
+        expense.close()
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description="Expense Tracker CLI")
+    parser.add_argument('--interval', type=int, help='Run continuously every N seconds', default=argparse.SUPPRESS)
+    parser.add_argument('--month', type=int, help='Month for summary (1–12)', default=argparse.SUPPRESS)
+    parser.add_argument('--year', type=int, help='Year for summary (e.g., 2024)', default=argparse.SUPPRESS)
+
+    args = parser.parse_args()
+    mode, error = validate_args(args)
+
+    if mode == "continuous":
+        run_continuous(args.interval) if hasattr(args, "interval") else run_continuous()
+    elif mode == "monthly":
+        run_monthly_summary(args.month, args.year)
+    else:
+        parser.error("Invalid combination of arguments. Use --interval or --month and --year.")
diff --git a/tracker/validators.py b/tracker/validators.py
new file mode 100644
index 0000000..026ceee
--- /dev/null
+++ b/tracker/validators.py
@@ -0,0 +1,127 @@
+import functools
+import calendar
+
+
+def validate_sender_email(func):
+    """
+      A decorator to validate the presence of a `sender_email` attribute in the first argument of the wrapped function.
+
+      This decorator ensures that:
+      - The first argument passed to the function is an instance of a class.
+      - The instance has a `sender_email` attribute with a non-empty value.
+
+      Args:
+          func (callable): The function to be wrapped by the decorator.
+
+      Returns:
+          callable: The wrapped function with validation applied to the `sender_email` attribute.
+
+      Raises:
+          ValueError: If the first argument is not an instance of a class or if the `sender_email` attribute is missing or empty.
+
+      Notes:
+          - The `sender_email` attribute is expected to be present in the first argument of the wrapped function.
+          - If the validation fails, a `ValueError` is raised with an appropriate error message.
+    """
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        instance = args[0] if args else None
+        if instance is None or not hasattr(instance, "__class__"):
+            raise ValueError("First argument must be an instance of the class.")
+
+        sender_email = instance.sender_email if hasattr(instance, 'sender_email') else None
+        if not sender_email:
+            raise ValueError("Missing environment variable: ET_SENDER_EMAIL")
+        return func(*args, **kwargs)
+    return wrapper
+
+
+def validate_month_year(func):
+    """
+       A decorator to validate the `month` and `year` arguments passed to a function.
+
+       This decorator ensures that:
+       - The `year` argument is a 4-digit integer.
+       - The `month` argument is either an integer between 1 and 12 or a valid full month name (case-insensitive).
+
+       Args:
+           func (callable): The function to be wrapped by the decorator.
+
+       Returns:
+           callable: The wrapped function with validation applied to its `month` and `year` arguments.
+
+       Raises:
+           ValueError: If the `month` or `year` arguments are invalid.
+
+       Notes:
+           - The `month` and `year` arguments can be passed as keyword arguments (`kwargs`) or positional arguments (`args`).
+           - If the validation fails, a `ValueError` is raised with an appropriate error message.
+    """
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        # Get month and year from kwargs or args
+        month = kwargs.get('month') or (args[1] if len(args) > 0 else None)
+        year = kwargs.get('year') or (args[2] if len(args) > 1 else None)
+
+        # Validate year
+        if not isinstance(year, int)  or len(str(year)) != 4:
+            raise ValueError(f"Invalid year format: '{year}'. Year must be a 4-digit string.")
+
+        # Validate month
+        valid_months = [i for i in range(1, 13)]
+        valid_month_names = [m.lower() for m in calendar.month_name if m]
+
+        if isinstance(month, int):
+            if month not in valid_months:
+                raise ValueError(f"Invalid month: '{month}'. Must be '01'-'12' or full month name.")
+        elif isinstance(month, str):
+            if month.lower() not in valid_month_names:
+                raise ValueError(f"Invalid month: '{month}'. Must be '01'-'12' or full month name.")
+        else:
+            raise ValueError(f"Month must be a string. Got {type(month)} instead.")
+
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
+def validate_args(args) -> tuple:
+    """
+        Validates the combination of arguments provided to the function.
+
+        Args:
+            args: An object containing the following attributes:
+                - interval (bool): Indicates if the interval mode is enabled.
+                - month (str or None): The month value, expected as a string.
+                - year (str or None): The year value, expected as a string.
+
+        Returns:
+            tuple: A tuple containing:
+                - str: The validation result, which can be one of:
+                    - "error": Indicates an invalid combination of arguments.
+                    - "continuous": Indicates the interval mode is valid.
+                    - "monthly": Indicates the month and year combination is valid.
+                - str or None: An error message if the result is "error", otherwise None.
+
+        Raises:
+            ValueError: If the arguments do not meet the required conditions.
+
+        Notes:
+            - The function ensures that `--interval` cannot be used together with `--month` or `--year`.
+            - If `--interval` is provided, it returns "continuous".
+            - If both `--month` and `--year` are provided, it returns "monthly".
+            - If neither condition is met, it returns an error with an appropriate message.
+    """
+
+    has_interval = 'interval' in args
+    has_month = 'month' in args
+    has_year = 'year' in args
+
+    if has_interval and (has_month or has_year):
+        return "error", "Cannot use --interval with --month/--year together."
+    elif has_interval:
+        return "continuous", None
+    elif has_month and has_year:
+        return "monthly", None
+    else:
+        return "continuous", None