diff --git a/app/Service/LocalizationService.php b/app/Service/LocalizationService.php
index 7d145f41..b375c51a 100644
--- a/app/Service/LocalizationService.php
+++ b/app/Service/LocalizationService.php
@@ -155,9 +155,10 @@ class LocalizationService
     }
 
     /**
-     * Time group types have no server-side descriptor; Day and Week keys are ISO dates and
+     * Time group types have no server-side descriptor; their keys are ISO dates and are
      * formatted here instead. A Week key is the first day of that week, so it renders as the
-     * range it covers.
+     * range it covers. A Year key is already a bare year, so it is returned unchanged - it must
+     * not be parsed, Carbon reads a four digit string as a time of day.
      */
     public function formatTimeGroupKey(?string $key, TimeEntryAggregationType $groupType): ?string
     {
@@ -175,6 +176,13 @@ class LocalizationService
             return $this->formatDate($weekStart).' - '.$this->formatDate($weekStart->copy()->addDays(6));
         }
 
+        if ($groupType === TimeEntryAggregationType::Month) {
+            // Note: the leading "!" resets all fields the format does not name. Without it the
+            // day of the month is taken from today, and a day that the parsed month does not
+            // have overflows the date into the next month.
+            return Carbon::createFromFormat('!Y-m', $key)->format('F Y');
+        }
+
         return $key;
     }
 
diff --git a/resources/js/packages/ui/src/utils/time.test.ts b/resources/js/packages/ui/src/utils/time.test.ts
index 8c9923c7..6c62bd39 100644
--- a/resources/js/packages/ui/src/utils/time.test.ts
+++ b/resources/js/packages/ui/src/utils/time.test.ts
@@ -1,5 +1,10 @@
 import { describe, expect, test } from 'vitest';
-import { formatHumanReadableDuration, formatReportingDuration, formatWeekRange } from './time';
+import {
+    formatHumanReadableDuration,
+    formatMonth,
+    formatReportingDuration,
+    formatWeekRange,
+} from './time';
 
 const seconds = 14 * 3600 + 45 * 60 + 6; // 14h 45m 06s
 
@@ -60,3 +65,9 @@ describe('formatWeekRange', () => {
         );
     });
 });
+
+describe('formatMonth', () => {
+    test('renders the name of the month that the key covers', () => {
+        expect(formatMonth('2001-02')).toBe('February 2001');
+    });
+});
diff --git a/resources/js/packages/ui/src/utils/time.ts b/resources/js/packages/ui/src/utils/time.ts
index 7a7a93be..41469075 100644
--- a/resources/js/packages/ui/src/utils/time.ts
+++ b/resources/js/packages/ui/src/utils/time.ts
@@ -245,6 +245,15 @@ export function formatWeekRange(date: string, format?: DateFormat): string {
     return `${formatDate(date, format)} - ${formatDate(end, format)}`;
 }
 
+/*
+ * Returns the month that the given key falls in. There is no `DateFormat` variant for a
+ * month, so this is not affected by the organization date format.
+ * @param date - a month, in the format of 'YYYY-MM'
+ */
+export function formatMonth(date: string): string {
+    return getDayJsInstance()(date).format('MMMM YYYY');
+}
+
 /*
  * Returns a human readable date format.
  * @param date - date in the format of 'YYYY-MM-DD'
diff --git a/resources/js/utils/useReporting.ts b/resources/js/utils/useReporting.ts
index 8e0181ef..9d3f5a66 100644
--- a/resources/js/utils/useReporting.ts
+++ b/resources/js/utils/useReporting.ts
@@ -15,7 +15,12 @@ import {
 } from '@heroicons/vue/16/solid';
 import { Coffee } from '@lucide/vue';
 import BillableIcon from '@/packages/ui/src/Icons/BillableIcon.vue';
-import { type DateFormat, formatDate, formatWeekRange } from '@/packages/ui/src/utils/time';
+import {
+    type DateFormat,
+    formatDate,
+    formatMonth,
+    formatWeekRange,
+} from '@/packages/ui/src/utils/time';
 
 export type GroupingOption =
     | 'project'
@@ -27,7 +32,9 @@ export type GroupingOption =
     | 'tag'
     | 'type'
     | 'day'
-    | 'week';
+    | 'week'
+    | 'month'
+    | 'year';
 
 export const useReportingStore = defineStore('reporting', () => {
     // Cache query composables to avoid creating new subscriptions on every call
@@ -94,6 +101,10 @@ export const useReportingStore = defineStore('reporting', () => {
         if (type === 'week') {
             return formatWeekRange(key, dateFormat);
         }
+        if (type === 'month') {
+            return formatMonth(key);
+        }
+        // A `year` key is already a bare year, so it falls through unchanged.
         return key;
     }
 
diff --git a/tests/Unit/Service/LocalizationServiceTest.php b/tests/Unit/Service/LocalizationServiceTest.php
index c1e3bf9d..09c85416 100644
--- a/tests/Unit/Service/LocalizationServiceTest.php
+++ b/tests/Unit/Service/LocalizationServiceTest.php
@@ -364,14 +364,27 @@ class LocalizationServiceTest extends TestCaseWithDatabase
         $this->assertSame('29/12/2025 - 04/01/2026', $formatted);
     }
 
-    public function test_format_time_group_key_does_not_change_month_year_and_entity_group_types(): void
+    public function test_format_time_group_key_formats_a_month_key_and_does_not_change_year_and_entity_group_types(): void
     {
         // Arrange
         $this->localizationService->setDateFormat(DateFormat::SlashSeparatedDDMMYYYY);
 
         // Act & Assert
-        $this->assertSame('2001-02', $this->localizationService->formatTimeGroupKey('2001-02', TimeEntryAggregationType::Month));
+        $this->assertSame('February 2001', $this->localizationService->formatTimeGroupKey('2001-02', TimeEntryAggregationType::Month));
         $this->assertSame('2001', $this->localizationService->formatTimeGroupKey('2001', TimeEntryAggregationType::Year));
         $this->assertSame('some-uuid', $this->localizationService->formatTimeGroupKey('some-uuid', TimeEntryAggregationType::Project));
     }
+
+    public function test_format_time_group_key_formats_a_month_key_independently_of_the_current_day_of_month(): void
+    {
+        // Arrange
+        // Note: the current day of the month must not leak into the parsed month. The 31st does
+        // not exist in April, so a leaked day overflows the date into the following month.
+        $this->travelTo(Carbon::create(2026, 8, 31, 12, 0, 0, 'UTC'));
+
+        // Act & Assert
+        $this->assertSame('February 2001', $this->localizationService->formatTimeGroupKey('2001-02', TimeEntryAggregationType::Month));
+        $this->assertSame('April 2026', $this->localizationService->formatTimeGroupKey('2026-04', TimeEntryAggregationType::Month));
+        $this->assertSame('December 2026', $this->localizationService->formatTimeGroupKey('2026-12', TimeEntryAggregationType::Month));
+    }
 }