diff --git a/frontend/components/Task/TaskDetails/TaskDeferUntilCard.tsx b/frontend/components/Task/TaskDetails/TaskDeferUntilCard.tsx
index 953963b..c74896d 100644
--- a/frontend/components/Task/TaskDetails/TaskDeferUntilCard.tsx
+++ b/frontend/components/Task/TaskDetails/TaskDeferUntilCard.tsx
@@ -1,9 +1,13 @@
-import React, { useMemo } from 'react';
+import React from 'react';
 import { useTranslation } from 'react-i18next';
 import { ClockIcon } from '@heroicons/react/24/outline';
 import TaskDeferUntilSection from '../TaskForm/TaskDeferUntilSection';
 import { Task } from '../../../entities/Task';
-import { resolveUserLocale } from '../../../utils/localeUtils';
+import {
+    formatDateTimeByCountry,
+    getUserTimezone,
+} from '../../../utils/dateUtils';
+import { getCountryFromTimezone } from '../../../utils/localeUtils';
 
 interface TaskDeferUntilCardProps {
     task: Task;
@@ -24,23 +28,16 @@ const TaskDeferUntilCard: React.FC<TaskDeferUntilCardProps> = ({
     onSave,
     onCancel,
 }) => {
-    const { t, i18n } = useTranslation();
-    const displayLocale = useMemo(
-        () => resolveUserLocale(i18n.language),
-        [i18n.language]
-    );
+    const { t } = useTranslation();
 
     const getDeferUntilDisplay = (deferUntil: string) => {
         const date = new Date(deferUntil);
         if (Number.isNaN(date.getTime())) return null;
 
-        const formattedDateTime = date.toLocaleString(displayLocale, {
-            day: '2-digit',
-            month: '2-digit',
-            year: 'numeric',
-            hour: '2-digit',
-            minute: '2-digit',
-        });
+        // Format datetime based on user's timezone-derived country
+        const timezone = getUserTimezone();
+        const country = getCountryFromTimezone(timezone);
+        const formattedDateTime = formatDateTimeByCountry(date, country);
 
         const now = new Date();
         const diffMs = date.getTime() - now.getTime();
diff --git a/frontend/components/Task/TaskDetails/TaskDueDateCard.tsx b/frontend/components/Task/TaskDetails/TaskDueDateCard.tsx
index 4d281ec..8c75d68 100644
--- a/frontend/components/Task/TaskDetails/TaskDueDateCard.tsx
+++ b/frontend/components/Task/TaskDetails/TaskDueDateCard.tsx
@@ -1,4 +1,4 @@
-import React, { useMemo } from 'react';
+import React from 'react';
 import { useTranslation } from 'react-i18next';
 import {
     CalendarIcon,
@@ -6,8 +6,12 @@ import {
 } from '@heroicons/react/24/outline';
 import TaskDueDateSection from '../TaskForm/TaskDueDateSection';
 import { Task } from '../../../entities/Task';
-import { parseDateString } from '../../../utils/dateUtils';
-import { resolveUserLocale } from '../../../utils/localeUtils';
+import {
+    parseDateString,
+    formatDateByCountry,
+    getUserTimezone,
+} from '../../../utils/dateUtils';
+import { getCountryFromTimezone } from '../../../utils/localeUtils';
 
 interface TaskDueDateCardProps {
     task: Task;
@@ -28,21 +32,16 @@ const TaskDueDateCard: React.FC<TaskDueDateCardProps> = ({
     onSave,
     onCancel,
 }) => {
-    const { t, i18n } = useTranslation();
-    const displayLocale = useMemo(
-        () => resolveUserLocale(i18n.language),
-        [i18n.language]
-    );
+    const { t } = useTranslation();
 
     const getDueDateDisplay = (dueDate: string) => {
         const date = parseDateString(dueDate);
         if (!date) return null;
 
-        const formattedDate = date.toLocaleDateString(displayLocale, {
-            day: '2-digit',
-            month: '2-digit',
-            year: 'numeric',
-        });
+        // Format date based on user's timezone-derived country
+        const timezone = getUserTimezone();
+        const country = getCountryFromTimezone(timezone);
+        const formattedDate = formatDateByCountry(date, country);
 
         const today = new Date();
         today.setHours(0, 0, 0, 0);
diff --git a/frontend/utils/dateUtils.test.ts b/frontend/utils/dateUtils.test.ts
new file mode 100644
index 0000000..ae591f3
--- /dev/null
+++ b/frontend/utils/dateUtils.test.ts
@@ -0,0 +1,249 @@
+import { formatDateByCountry, formatDateTimeByCountry } from './dateUtils';
+
+describe('formatDateByCountry', () => {
+    // Test date: March 15, 2026 at 10:30 AM
+    const testDate = new Date('2026-03-15T10:30:00');
+
+    describe('DD/MM/YYYY format (European and most global)', () => {
+        it('formats dates in DD/MM/YYYY for Greece', () => {
+            expect(formatDateByCountry(testDate, 'GR')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for United Kingdom', () => {
+            expect(formatDateByCountry(testDate, 'GB')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for France', () => {
+            expect(formatDateByCountry(testDate, 'FR')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for Germany', () => {
+            expect(formatDateByCountry(testDate, 'DE')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for Italy', () => {
+            expect(formatDateByCountry(testDate, 'IT')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for Spain', () => {
+            expect(formatDateByCountry(testDate, 'ES')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for Australia', () => {
+            expect(formatDateByCountry(testDate, 'AU')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for India', () => {
+            expect(formatDateByCountry(testDate, 'IN')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for Brazil', () => {
+            expect(formatDateByCountry(testDate, 'BR')).toBe('15/03/2026');
+        });
+
+        it('formats dates in DD/MM/YYYY for South Africa', () => {
+            expect(formatDateByCountry(testDate, 'ZA')).toBe('15/03/2026');
+        });
+    });
+
+    describe('MM/DD/YYYY format (North America)', () => {
+        it('formats dates in MM/DD/YYYY for United States', () => {
+            expect(formatDateByCountry(testDate, 'US')).toBe('03/15/2026');
+        });
+
+        it('formats dates in MM/DD/YYYY for Canada', () => {
+            expect(formatDateByCountry(testDate, 'CA')).toBe('03/15/2026');
+        });
+
+        it('formats dates in MM/DD/YYYY for Philippines', () => {
+            expect(formatDateByCountry(testDate, 'PH')).toBe('03/15/2026');
+        });
+    });
+
+    describe('YYYY/MM/DD format (East Asia)', () => {
+        it('formats dates in YYYY/MM/DD for Japan', () => {
+            expect(formatDateByCountry(testDate, 'JP')).toBe('2026/03/15');
+        });
+
+        it('formats dates in YYYY/MM/DD for South Korea', () => {
+            expect(formatDateByCountry(testDate, 'KR')).toBe('2026/03/15');
+        });
+
+        it('formats dates in YYYY/MM/DD for China', () => {
+            expect(formatDateByCountry(testDate, 'CN')).toBe('2026/03/15');
+        });
+
+        it('formats dates in YYYY/MM/DD for Taiwan', () => {
+            expect(formatDateByCountry(testDate, 'TW')).toBe('2026/03/15');
+        });
+    });
+
+    describe('Default and edge cases', () => {
+        it('uses DD/MM/YYYY as default format when country is null', () => {
+            expect(formatDateByCountry(testDate, null)).toBe('15/03/2026');
+        });
+
+        it('uses DD/MM/YYYY as default format when country is undefined', () => {
+            expect(formatDateByCountry(testDate, undefined)).toBe('15/03/2026');
+        });
+
+        it('uses DD/MM/YYYY as default format when country is unknown', () => {
+            expect(formatDateByCountry(testDate, 'UNKNOWN')).toBe('15/03/2026');
+        });
+
+        it('uses DD/MM/YYYY as default format for empty string', () => {
+            expect(formatDateByCountry(testDate, '')).toBe('15/03/2026');
+        });
+    });
+
+    describe('Date boundaries', () => {
+        it('formats dates with single-digit day correctly', () => {
+            const date = new Date('2026-03-05T10:00:00');
+            expect(formatDateByCountry(date, 'GR')).toBe('05/03/2026');
+            expect(formatDateByCountry(date, 'US')).toBe('03/05/2026');
+            expect(formatDateByCountry(date, 'JP')).toBe('2026/03/05');
+        });
+
+        it('formats dates with single-digit month correctly', () => {
+            const date = new Date('2026-01-15T10:00:00');
+            expect(formatDateByCountry(date, 'GR')).toBe('15/01/2026');
+            expect(formatDateByCountry(date, 'US')).toBe('01/15/2026');
+            expect(formatDateByCountry(date, 'JP')).toBe('2026/01/15');
+        });
+
+        it('formats end of month dates correctly', () => {
+            const date = new Date('2026-12-31T10:00:00');
+            expect(formatDateByCountry(date, 'GR')).toBe('31/12/2026');
+            expect(formatDateByCountry(date, 'US')).toBe('12/31/2026');
+            expect(formatDateByCountry(date, 'JP')).toBe('2026/12/31');
+        });
+
+        it('formats start of year dates correctly', () => {
+            const date = new Date('2026-01-01T10:00:00');
+            expect(formatDateByCountry(date, 'GR')).toBe('01/01/2026');
+            expect(formatDateByCountry(date, 'US')).toBe('01/01/2026');
+            expect(formatDateByCountry(date, 'JP')).toBe('2026/01/01');
+        });
+    });
+});
+
+describe('formatDateTimeByCountry', () => {
+    // Test datetime: March 15, 2026 at 14:30 (2:30 PM)
+    const testDate = new Date('2026-03-15T14:30:00');
+
+    describe('DD/MM/YYYY HH:MM format (European and most global)', () => {
+        it('formats datetime in DD/MM/YYYY HH:MM for Greece', () => {
+            expect(formatDateTimeByCountry(testDate, 'GR')).toBe(
+                '15/03/2026 14:30'
+            );
+        });
+
+        it('formats datetime in DD/MM/YYYY HH:MM for United Kingdom', () => {
+            expect(formatDateTimeByCountry(testDate, 'GB')).toBe(
+                '15/03/2026 14:30'
+            );
+        });
+
+        it('formats datetime in DD/MM/YYYY HH:MM for Germany', () => {
+            expect(formatDateTimeByCountry(testDate, 'DE')).toBe(
+                '15/03/2026 14:30'
+            );
+        });
+
+        it('formats datetime in DD/MM/YYYY HH:MM for Australia', () => {
+            expect(formatDateTimeByCountry(testDate, 'AU')).toBe(
+                '15/03/2026 14:30'
+            );
+        });
+    });
+
+    describe('MM/DD/YYYY HH:MM format (North America)', () => {
+        it('formats datetime in MM/DD/YYYY HH:MM for United States', () => {
+            expect(formatDateTimeByCountry(testDate, 'US')).toBe(
+                '03/15/2026 14:30'
+            );
+        });
+
+        it('formats datetime in MM/DD/YYYY HH:MM for Canada', () => {
+            expect(formatDateTimeByCountry(testDate, 'CA')).toBe(
+                '03/15/2026 14:30'
+            );
+        });
+    });
+
+    describe('YYYY/MM/DD HH:MM format (East Asia)', () => {
+        it('formats datetime in YYYY/MM/DD HH:MM for Japan', () => {
+            expect(formatDateTimeByCountry(testDate, 'JP')).toBe(
+                '2026/03/15 14:30'
+            );
+        });
+
+        it('formats datetime in YYYY/MM/DD HH:MM for South Korea', () => {
+            expect(formatDateTimeByCountry(testDate, 'KR')).toBe(
+                '2026/03/15 14:30'
+            );
+        });
+
+        it('formats datetime in YYYY/MM/DD HH:MM for China', () => {
+            expect(formatDateTimeByCountry(testDate, 'CN')).toBe(
+                '2026/03/15 14:30'
+            );
+        });
+    });
+
+    describe('Time formatting', () => {
+        it('uses 24-hour format for all countries', () => {
+            const morning = new Date('2026-03-15T09:15:00');
+            const afternoon = new Date('2026-03-15T15:45:00');
+            const midnight = new Date('2026-03-15T00:00:00');
+            const noon = new Date('2026-03-15T12:00:00');
+
+            expect(formatDateTimeByCountry(morning, 'US')).toBe(
+                '03/15/2026 09:15'
+            );
+            expect(formatDateTimeByCountry(afternoon, 'US')).toBe(
+                '03/15/2026 15:45'
+            );
+            expect(formatDateTimeByCountry(midnight, 'US')).toBe(
+                '03/15/2026 00:00'
+            );
+            expect(formatDateTimeByCountry(noon, 'US')).toBe(
+                '03/15/2026 12:00'
+            );
+        });
+
+        it('formats minutes with leading zero', () => {
+            const date = new Date('2026-03-15T14:05:00');
+            expect(formatDateTimeByCountry(date, 'GR')).toBe(
+                '15/03/2026 14:05'
+            );
+        });
+
+        it('formats hours with leading zero for single digits', () => {
+            const date = new Date('2026-03-15T08:30:00');
+            expect(formatDateTimeByCountry(date, 'GR')).toBe(
+                '15/03/2026 08:30'
+            );
+        });
+    });
+
+    describe('Default and edge cases', () => {
+        it('uses DD/MM/YYYY HH:MM as default format when country is null', () => {
+            expect(formatDateTimeByCountry(testDate, null)).toBe(
+                '15/03/2026 14:30'
+            );
+        });
+
+        it('uses DD/MM/YYYY HH:MM as default format when country is undefined', () => {
+            expect(formatDateTimeByCountry(testDate, undefined)).toBe(
+                '15/03/2026 14:30'
+            );
+        });
+
+        it('uses DD/MM/YYYY HH:MM as default format when country is unknown', () => {
+            expect(formatDateTimeByCountry(testDate, 'UNKNOWN')).toBe(
+                '15/03/2026 14:30'
+            );
+        });
+    });
+});
diff --git a/frontend/utils/dateUtils.ts b/frontend/utils/dateUtils.ts
index d1722d5..6b096c8 100644
--- a/frontend/utils/dateUtils.ts
+++ b/frontend/utils/dateUtils.ts
@@ -293,3 +293,141 @@ export const isTaskOverdueInTodayPlan = (task: {
     // are likely to have been sitting there for a while
     return createdDate.getTime() < yesterday.getTime();
 };
+
+/**
+ * Maps ISO 3166-1 country codes to date format patterns.
+ * Used to ensure consistent date formatting based on regional conventions,
+ * independent of browser locale support.
+ *
+ * @returns Object mapping country code to date-fns format string
+ */
+const getCountryDateFormats = (): Record<string, string> => ({
+    // DD/MM/YYYY format (most common globally - European standard)
+    AT: 'dd/MM/yyyy', // Austria
+    BE: 'dd/MM/yyyy', // Belgium
+    BG: 'dd/MM/yyyy', // Bulgaria
+    CH: 'dd/MM/yyyy', // Switzerland
+    CY: 'dd/MM/yyyy', // Cyprus
+    CZ: 'dd/MM/yyyy', // Czech Republic
+    DE: 'dd/MM/yyyy', // Germany
+    DK: 'dd/MM/yyyy', // Denmark
+    EE: 'dd/MM/yyyy', // Estonia
+    ES: 'dd/MM/yyyy', // Spain
+    FI: 'dd/MM/yyyy', // Finland
+    FR: 'dd/MM/yyyy', // France
+    GB: 'dd/MM/yyyy', // United Kingdom
+    GR: 'dd/MM/yyyy', // Greece
+    HR: 'dd/MM/yyyy', // Croatia
+    IE: 'dd/MM/yyyy', // Ireland
+    IS: 'dd/MM/yyyy', // Iceland
+    IT: 'dd/MM/yyyy', // Italy
+    LT: 'dd/MM/yyyy', // Lithuania
+    LU: 'dd/MM/yyyy', // Luxembourg
+    LV: 'dd/MM/yyyy', // Latvia
+    MT: 'dd/MM/yyyy', // Malta
+    NL: 'dd/MM/yyyy', // Netherlands
+    NO: 'dd/MM/yyyy', // Norway
+    PL: 'dd/MM/yyyy', // Poland
+    PT: 'dd/MM/yyyy', // Portugal
+    RO: 'dd/MM/yyyy', // Romania
+    SE: 'dd/MM/yyyy', // Sweden
+    SI: 'dd/MM/yyyy', // Slovenia
+    SK: 'dd/MM/yyyy', // Slovakia
+    TR: 'dd/MM/yyyy', // Turkey
+    RU: 'dd/MM/yyyy', // Russia
+
+    // DD/MM/YYYY format (Africa)
+    DZ: 'dd/MM/yyyy', // Algeria
+    EG: 'dd/MM/yyyy', // Egypt
+    GH: 'dd/MM/yyyy', // Ghana
+    KE: 'dd/MM/yyyy', // Kenya
+    MA: 'dd/MM/yyyy', // Morocco
+    NG: 'dd/MM/yyyy', // Nigeria
+    TN: 'dd/MM/yyyy', // Tunisia
+    ZA: 'dd/MM/yyyy', // South Africa
+
+    // DD/MM/YYYY format (Asia/Pacific)
+    AU: 'dd/MM/yyyy', // Australia
+    BD: 'dd/MM/yyyy', // Bangladesh
+    FJ: 'dd/MM/yyyy', // Fiji
+    GU: 'dd/MM/yyyy', // Guam
+    HK: 'dd/MM/yyyy', // Hong Kong
+    ID: 'dd/MM/yyyy', // Indonesia
+    IN: 'dd/MM/yyyy', // India
+    MY: 'dd/MM/yyyy', // Malaysia
+    NZ: 'dd/MM/yyyy', // New Zealand
+    PK: 'dd/MM/yyyy', // Pakistan
+    SG: 'dd/MM/yyyy', // Singapore
+    TH: 'dd/MM/yyyy', // Thailand
+
+    // DD/MM/YYYY format (Middle East)
+    AE: 'dd/MM/yyyy', // United Arab Emirates
+    IL: 'dd/MM/yyyy', // Israel
+    IR: 'dd/MM/yyyy', // Iran
+    SA: 'dd/MM/yyyy', // Saudi Arabia
+
+    // DD/MM/YYYY format (Americas - except US/CA)
+    AR: 'dd/MM/yyyy', // Argentina
+    BR: 'dd/MM/yyyy', // Brazil
+    CL: 'dd/MM/yyyy', // Chile
+    CO: 'dd/MM/yyyy', // Colombia
+    MX: 'dd/MM/yyyy', // Mexico
+    PE: 'dd/MM/yyyy', // Peru
+    VE: 'dd/MM/yyyy', // Venezuela
+
+    // MM/DD/YYYY format (North America and some others)
+    US: 'MM/dd/yyyy', // United States
+    CA: 'MM/dd/yyyy', // Canada
+    PH: 'MM/dd/yyyy', // Philippines
+
+    // YYYY/MM/DD format (East Asia - ISO-like format)
+    CN: 'yyyy/MM/dd', // China
+    JP: 'yyyy/MM/dd', // Japan
+    KR: 'yyyy/MM/dd', // South Korea
+    TW: 'yyyy/MM/dd', // Taiwan
+});
+
+/**
+ * Formats a date using country-specific format pattern.
+ * This provides consistent date formatting independent of browser locale support.
+ *
+ * @param date - Date to format
+ * @param country - ISO 3166-1 country code (optional)
+ * @returns Formatted date string (e.g., "15/03/2026" for Greece, "03/15/2026" for US)
+ */
+export const formatDateByCountry = (
+    date: Date,
+    country?: string | null
+): string => {
+    const formats = getCountryDateFormats();
+
+    // Use country-specific format if available, otherwise default to DD/MM/YYYY
+    const formatPattern =
+        country && formats[country] ? formats[country] : 'dd/MM/yyyy';
+
+    return format(date, formatPattern);
+};
+
+/**
+ * Formats a datetime using country-specific date format + 24-hour time.
+ * This provides consistent datetime formatting independent of browser locale support.
+ *
+ * @param date - Date to format
+ * @param country - ISO 3166-1 country code (optional)
+ * @returns Formatted datetime string (e.g., "15/03/2026 14:30" for Greece)
+ */
+export const formatDateTimeByCountry = (
+    date: Date,
+    country?: string | null
+): string => {
+    const formats = getCountryDateFormats();
+
+    // Use country-specific format if available, otherwise default to DD/MM/YYYY
+    const datePattern =
+        country && formats[country] ? formats[country] : 'dd/MM/yyyy';
+
+    // Combine date pattern with 24-hour time format
+    const datetimePattern = `${datePattern} HH:mm`;
+
+    return format(date, datetimePattern);
+};