diff --git a/src/accounting/report/reports/balance_sheet.py b/src/accounting/report/reports/balance_sheet.py
index c5ae4c4..21d9dd1 100644
--- a/src/accounting/report/reports/balance_sheet.py
+++ b/src/accounting/report/reports/balance_sheet.py
@@ -28,7 +28,7 @@ from accounting.models import Currency, BaseAccount, Account, Transaction, \
     JournalEntry
 from accounting.report.period import Period
 from .utils.base_report import BaseReport
-from .utils.csv_export import BaseCSVRow, csv_download
+from .utils.csv_export import BaseCSVRow, csv_download, period_spec
 from .utils.option_link import OptionLink
 from .utils.page_params import PageParams
 from .utils.period_choosers import BalanceSheetPeriodChooser
@@ -428,7 +428,8 @@ class BalanceSheet(BaseReport):
         :return: The response of the report for download.
         """
         filename: str = "balance-sheet-{currency}-{period}.csv"\
-            .format(currency=self.__currency.code, period=self.__period.spec)
+            .format(currency=self.__currency.code,
+                    period=period_spec(self.__period))
         return csv_download(filename, self.__get_csv_rows())
 
     def __get_csv_rows(self) -> list[CSVRow]:
diff --git a/src/accounting/report/reports/income_expenses.py b/src/accounting/report/reports/income_expenses.py
index dc492d4..fb1d7f2 100644
--- a/src/accounting/report/reports/income_expenses.py
+++ b/src/accounting/report/reports/income_expenses.py
@@ -30,7 +30,7 @@ from accounting.report.income_expense_account import IncomeExpensesAccount
 from accounting.report.period import Period
 from accounting.utils.pagination import Pagination
 from .utils.base_report import BaseReport
-from .utils.csv_export import BaseCSVRow, csv_download
+from .utils.csv_export import BaseCSVRow, csv_download, period_spec
 from .utils.option_link import OptionLink
 from .utils.page_params import PageParams
 from .utils.period_choosers import IncomeExpensesPeriodChooser
@@ -421,7 +421,7 @@ class IncomeExpenses(BaseReport):
         """
         filename: str = "income-expenses-{currency}-{account}-{period}.csv"\
             .format(currency=self.__currency.code, account=self.__account.code,
-                    period=self.__period.spec)
+                    period=period_spec(self.__period))
         return csv_download(filename, self.__get_csv_rows())
 
     def __get_csv_rows(self) -> list[CSVRow]:
diff --git a/src/accounting/report/reports/income_statement.py b/src/accounting/report/reports/income_statement.py
index 061c845..0ac5464 100644
--- a/src/accounting/report/reports/income_statement.py
+++ b/src/accounting/report/reports/income_statement.py
@@ -28,7 +28,7 @@ from accounting.models import Currency, BaseAccount, Account, Transaction, \
     JournalEntry
 from accounting.report.period import Period
 from .utils.base_report import BaseReport
-from .utils.csv_export import BaseCSVRow, csv_download
+from .utils.csv_export import BaseCSVRow, csv_download, period_spec
 from .utils.option_link import OptionLink
 from .utils.page_params import PageParams
 from .utils.period_choosers import IncomeStatementPeriodChooser
@@ -310,7 +310,8 @@ class IncomeStatement(BaseReport):
         :return: The response of the report for download.
         """
         filename: str = "income-statement-{currency}-{period}.csv"\
-            .format(currency=self.__currency.code, period=self.__period.spec)
+            .format(currency=self.__currency.code,
+                    period=period_spec(self.__period))
         return csv_download(filename, self.__get_csv_rows())
 
     def __get_csv_rows(self) -> list[CSVRow]:
diff --git a/src/accounting/report/reports/journal.py b/src/accounting/report/reports/journal.py
index 5e03186..32a70b1 100644
--- a/src/accounting/report/reports/journal.py
+++ b/src/accounting/report/reports/journal.py
@@ -29,7 +29,7 @@ from accounting.models import Currency, Account, Transaction, JournalEntry
 from accounting.report.period import Period
 from accounting.utils.pagination import Pagination
 from .utils.base_report import BaseReport
-from .utils.csv_export import BaseCSVRow, csv_download
+from .utils.csv_export import BaseCSVRow, csv_download, period_spec
 from .utils.page_params import PageParams
 from .utils.period_choosers import JournalPeriodChooser
 from .utils.report_chooser import ReportChooser
@@ -208,7 +208,7 @@ class Journal(BaseReport):
 
         :return: The response of the report for download.
         """
-        filename: str = f"journal-{self.__period.spec}.csv"
+        filename: str = f"journal-{period_spec(self.__period)}.csv"
         return csv_download(filename, self.__get_csv_rows())
 
     def __get_csv_rows(self) -> list[CSVRow]:
diff --git a/src/accounting/report/reports/ledger.py b/src/accounting/report/reports/ledger.py
index 6e6e659..5b91e94 100644
--- a/src/accounting/report/reports/ledger.py
+++ b/src/accounting/report/reports/ledger.py
@@ -29,7 +29,7 @@ from accounting.models import Currency, Account, Transaction, JournalEntry
 from accounting.report.period import Period
 from accounting.utils.pagination import Pagination
 from .utils.base_report import BaseReport
-from .utils.csv_export import BaseCSVRow, csv_download
+from .utils.csv_export import BaseCSVRow, csv_download, period_spec
 from .utils.option_link import OptionLink
 from .utils.page_params import PageParams
 from .utils.period_choosers import LedgerPeriodChooser
@@ -375,7 +375,7 @@ class Ledger(BaseReport):
         """
         filename: str = "ledger-{currency}-{account}-{period}.csv"\
             .format(currency=self.__currency.code, account=self.__account.code,
-                    period=self.__period.spec)
+                    period=period_spec(self.__period))
         return csv_download(filename, self.__get_csv_rows())
 
     def __get_csv_rows(self) -> list[CSVRow]:
diff --git a/src/accounting/report/reports/trial_balance.py b/src/accounting/report/reports/trial_balance.py
index 8c06a63..ac93118 100644
--- a/src/accounting/report/reports/trial_balance.py
+++ b/src/accounting/report/reports/trial_balance.py
@@ -27,7 +27,7 @@ from accounting.locale import gettext
 from accounting.models import Currency, Account, Transaction, JournalEntry
 from accounting.report.period import Period
 from .utils.base_report import BaseReport
-from .utils.csv_export import BaseCSVRow, csv_download
+from .utils.csv_export import BaseCSVRow, csv_download, period_spec
 from .utils.option_link import OptionLink
 from .utils.page_params import PageParams
 from .utils.period_choosers import TrialBalancePeriodChooser
@@ -234,7 +234,8 @@ class TrialBalance(BaseReport):
         :return: The response of the report for download.
         """
         filename: str = "trial-balance-{currency}-{period}.csv"\
-            .format(currency=self.__currency.code, period=self.__period.spec)
+            .format(currency=self.__currency.code,
+                    period=period_spec(self.__period))
         return csv_download(filename, self.__get_csv_rows())
 
     def __get_csv_rows(self) -> list[CSVRow]:
diff --git a/src/accounting/report/reports/utils/csv_export.py b/src/accounting/report/reports/utils/csv_export.py
index a1874d4..a7d412d 100644
--- a/src/accounting/report/reports/utils/csv_export.py
+++ b/src/accounting/report/reports/utils/csv_export.py
@@ -19,11 +19,14 @@
 """
 import csv
 from abc import ABC, abstractmethod
+from datetime import timedelta
 from decimal import Decimal
 from io import StringIO
 
 from flask import Response
 
+from accounting.report.period import Period
+
 
 class BaseCSVRow(ABC):
     """The base CSV row."""
@@ -52,3 +55,36 @@ def csv_download(filename: str, rows: list[BaseCSVRow]) -> Response:
         response.headers["Content-Disposition"] \
             = f"attachment; filename={filename}"
         return response
+
+
+def period_spec(period: Period) -> str:
+    """Constructs the period specification to be used in the filename.
+
+    :param period: The period.
+    :return: The period specification to be used in the filename.
+    """
+    start: str | None = None
+    if period.start is not None:
+        if period.start.month == 1 and period.start.day == 1:
+            start = str(period.start.year)
+        elif period.start.day == 1:
+            start = period.start.strftime("%Y%m")
+        else:
+            start = period.start.strftime("%Y%m%d")
+    end: str | None = None
+    if period.end is not None:
+        if period.end.month == 12 and period.end.day == 31:
+            end = str(period.end.year)
+        elif (period.end + timedelta(days=1)).day == 1:
+            end = period.end.strftime("%Y%m")
+        else:
+            end = period.end.strftime("%Y%m%d")
+    if start == end:
+        return start
+    if period.start is None and period.end is None:
+        return "all-time"
+    if period.start is None:
+        return f"until-{end}"
+    if period.end is None:
+        return f"since-{start}"
+    return f"{start}-{end}"