diff --git a/src/accounting/report/converters.py b/src/accounting/report/converters.py
index d0733a5..d455097 100644
--- a/src/accounting/report/converters.py
+++ b/src/accounting/report/converters.py
@@ -23,8 +23,8 @@ from flask import abort
 from werkzeug.routing import BaseConverter
 
 from accounting.models import Account
+from accounting.report.period import Period
 from .utils.income_expense_account import IncomeExpensesAccount
-from .utils.period import Period
 
 
 class PeriodConverter(BaseConverter):
diff --git a/src/accounting/report/period/__init__.py b/src/accounting/report/period/__init__.py
new file mode 100644
index 0000000..6034604
--- /dev/null
+++ b/src/accounting/report/period/__init__.py
@@ -0,0 +1,21 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/9
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The period utility.
+
+"""
+from .period import Period
+from .period_chooser import PeriodChooser
diff --git a/src/accounting/report/utils/period.py b/src/accounting/report/period/period.py
similarity index 100%
rename from src/accounting/report/utils/period.py
rename to src/accounting/report/period/period.py
diff --git a/src/accounting/report/utils/period_chooser.py b/src/accounting/report/period/period_chooser.py
similarity index 100%
rename from src/accounting/report/utils/period_chooser.py
rename to src/accounting/report/period/period_chooser.py
diff --git a/src/accounting/report/reports/balance_sheet.py b/src/accounting/report/reports/balance_sheet.py
index 2de235b..ea0bd17 100644
--- a/src/accounting/report/reports/balance_sheet.py
+++ b/src/accounting/report/reports/balance_sheet.py
@@ -26,13 +26,12 @@ from accounting import db
 from accounting.locale import gettext
 from accounting.models import Currency, BaseAccount, Account, Transaction, \
     JournalEntry
+from accounting.report.period import Period, PeriodChooser
 from accounting.report.utils.base_page_params import BasePageParams
 from accounting.report.utils.base_report import BaseReport
 from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
     period_spec
 from accounting.report.utils.option_link import OptionLink
-from accounting.report.utils.period import Period
-from accounting.report.utils.period_chooser import PeriodChooser
 from accounting.report.utils.report_chooser import ReportChooser
 from accounting.report.utils.report_type import ReportType
 from accounting.report.utils.urls import ledger_url, balance_sheet_url, \
diff --git a/src/accounting/report/reports/income_expenses.py b/src/accounting/report/reports/income_expenses.py
index 7e4af3c..6a3a831 100644
--- a/src/accounting/report/reports/income_expenses.py
+++ b/src/accounting/report/reports/income_expenses.py
@@ -27,6 +27,7 @@ from sqlalchemy.orm import selectinload
 from accounting import db
 from accounting.locale import gettext
 from accounting.models import Currency, Account, Transaction, JournalEntry
+from accounting.report.period import Period, PeriodChooser
 from accounting.report.utils.base_page_params import BasePageParams
 from accounting.report.utils.base_report import BaseReport
 from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
@@ -34,8 +35,6 @@ from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
 from accounting.report.utils.income_expense_account import \
     IncomeExpensesAccount
 from accounting.report.utils.option_link import OptionLink
-from accounting.report.utils.period import Period
-from accounting.report.utils.period_chooser import PeriodChooser
 from accounting.report.utils.report_chooser import ReportChooser
 from accounting.report.utils.report_type import ReportType
 from accounting.report.utils.urls import income_expenses_url
diff --git a/src/accounting/report/reports/income_statement.py b/src/accounting/report/reports/income_statement.py
index 5f3d295..655ae6e 100644
--- a/src/accounting/report/reports/income_statement.py
+++ b/src/accounting/report/reports/income_statement.py
@@ -26,13 +26,12 @@ from accounting import db
 from accounting.locale import gettext
 from accounting.models import Currency, BaseAccount, Account, Transaction, \
     JournalEntry
+from accounting.report.period import Period, PeriodChooser
 from accounting.report.utils.base_page_params import BasePageParams
 from accounting.report.utils.base_report import BaseReport
 from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
     period_spec
 from accounting.report.utils.option_link import OptionLink
-from accounting.report.utils.period import Period
-from accounting.report.utils.period_chooser import PeriodChooser
 from accounting.report.utils.report_chooser import ReportChooser
 from accounting.report.utils.report_type import ReportType
 from accounting.report.utils.urls import ledger_url, income_statement_url
diff --git a/src/accounting/report/reports/journal.py b/src/accounting/report/reports/journal.py
index a5bcdb2..45243d7 100644
--- a/src/accounting/report/reports/journal.py
+++ b/src/accounting/report/reports/journal.py
@@ -26,12 +26,11 @@ from sqlalchemy.orm import selectinload
 
 from accounting.locale import gettext
 from accounting.models import Currency, Account, Transaction, JournalEntry
+from accounting.report.period import Period, PeriodChooser
 from accounting.report.utils.base_page_params import BasePageParams
 from accounting.report.utils.base_report import BaseReport
 from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
     period_spec
-from accounting.report.utils.period import Period
-from accounting.report.utils.period_chooser import PeriodChooser
 from accounting.report.utils.report_chooser import ReportChooser
 from accounting.report.utils.report_type import ReportType
 from accounting.report.utils.urls import journal_url
diff --git a/src/accounting/report/reports/ledger.py b/src/accounting/report/reports/ledger.py
index 9c297d9..43f9be8 100644
--- a/src/accounting/report/reports/ledger.py
+++ b/src/accounting/report/reports/ledger.py
@@ -27,13 +27,12 @@ from sqlalchemy.orm import selectinload
 from accounting import db
 from accounting.locale import gettext
 from accounting.models import Currency, Account, Transaction, JournalEntry
+from accounting.report.period import Period, PeriodChooser
 from accounting.report.utils.base_page_params import BasePageParams
 from accounting.report.utils.base_report import BaseReport
 from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
     period_spec
 from accounting.report.utils.option_link import OptionLink
-from accounting.report.utils.period import Period
-from accounting.report.utils.period_chooser import PeriodChooser
 from accounting.report.utils.report_chooser import ReportChooser
 from accounting.report.utils.report_type import ReportType
 from accounting.report.utils.urls import ledger_url
diff --git a/src/accounting/report/reports/trial_balance.py b/src/accounting/report/reports/trial_balance.py
index 16656d6..d6a84c2 100644
--- a/src/accounting/report/reports/trial_balance.py
+++ b/src/accounting/report/reports/trial_balance.py
@@ -25,13 +25,12 @@ from flask import Response, render_template
 from accounting import db
 from accounting.locale import gettext
 from accounting.models import Currency, Account, Transaction, JournalEntry
+from accounting.report.period import Period, PeriodChooser
 from accounting.report.utils.base_page_params import BasePageParams
 from accounting.report.utils.base_report import BaseReport
 from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
     period_spec
 from accounting.report.utils.option_link import OptionLink
-from accounting.report.utils.period import Period
-from accounting.report.utils.period_chooser import PeriodChooser
 from accounting.report.utils.report_chooser import ReportChooser
 from accounting.report.utils.report_type import ReportType
 from accounting.report.utils.urls import ledger_url, trial_balance_url
diff --git a/src/accounting/report/utils/csv_export.py b/src/accounting/report/utils/csv_export.py
index 1ab208b..ecf3b35 100644
--- a/src/accounting/report/utils/csv_export.py
+++ b/src/accounting/report/utils/csv_export.py
@@ -25,7 +25,7 @@ from io import StringIO
 
 from flask import Response
 
-from .period import Period
+from accounting.report.period import Period
 
 
 class BaseCSVRow(ABC):
diff --git a/src/accounting/report/utils/report_chooser.py b/src/accounting/report/utils/report_chooser.py
index 2b818ea..1200048 100644
--- a/src/accounting/report/utils/report_chooser.py
+++ b/src/accounting/report/utils/report_chooser.py
@@ -28,10 +28,10 @@ from flask_babel import LazyString
 from accounting import db
 from accounting.locale import gettext
 from accounting.models import Currency, Account
+from accounting.report.period import Period
 from accounting.template_globals import default_currency_code
 from .income_expense_account import IncomeExpensesAccount
 from .option_link import OptionLink
-from .period import Period
 from .report_type import ReportType
 from .urls import journal_url, ledger_url, income_expenses_url, \
     trial_balance_url, income_statement_url, balance_sheet_url
diff --git a/src/accounting/report/utils/urls.py b/src/accounting/report/utils/urls.py
index e5945ac..8ecbc58 100644
--- a/src/accounting/report/utils/urls.py
+++ b/src/accounting/report/utils/urls.py
@@ -20,8 +20,8 @@
 from flask import url_for
 
 from accounting.models import Currency, Account
+from accounting.report.period import Period
 from .income_expense_account import IncomeExpensesAccount
-from .period import Period
 
 
 def journal_url(period: Period) \
diff --git a/src/accounting/report/views.py b/src/accounting/report/views.py
index 7478c64..7e20be2 100644
--- a/src/accounting/report/views.py
+++ b/src/accounting/report/views.py
@@ -20,12 +20,12 @@
 from flask import Blueprint, request, Response
 
 from accounting.models import Currency, Account
+from accounting.report.period import Period
 from accounting.utils.permission import has_permission, can_view
 from .reports import Journal, Ledger, IncomeExpenses, TrialBalance, \
     IncomeStatement, BalanceSheet, Search
 from .template_filters import format_amount
 from .utils.income_expense_account import IncomeExpensesAccount
-from .utils.period import Period
 
 bp: Blueprint = Blueprint("report", __name__)
 """The view blueprint for the reports."""