diff --git a/AGENTS.md b/AGENTS.md
index 87ce61f..760f0a6 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -17,8 +17,8 @@ This repository is a **static GitHub Pages site**. There is no .NET / MAUI app,
 - Vanilla HTML/CSS/JS. Classic `<script>` tags (not ES modules) so `file://` and Pages both work.
 - Time format: results use `h:mm` (minutes always two digits). Worked time is two numeric fields (hours, minutes 0–59) so mobile keyboards do not need `:`.
 - Default start date: 1 January of the current calendar year (`app.js`). Default end date: today.
-- Working days: Monday–Friday minus ISO dates in `HOLIDAYS` (`worktime.js`). Compare `YYYY-MM-DD` strings; iterate in UTC.
-- Expected hours: **8 per working day** (`HOURS_PER_DAY`).
+- Working days: Monday–Friday minus holidays for every year overlapping the range (`holidaysForYear` in `worktime.js`). Compare `YYYY-MM-DD` strings; iterate in UTC.
+- Expected hours: **8 per working day** (`HOURS_PER_DAY`). A full non-leap year where all configured holidays fall on weekdays is **252 days / 2016 hours**, not 261 weekdays / 2088 hours.
 - UI language: Spanish. README and this file: English.
 - Commit messages: English.
 
@@ -35,7 +35,13 @@ GitHub Pages URL: `https://cesarordazv.github.io/WorktimeCalculator/`
 
 ### Add or update holidays
 
-Edit the `HOLIDAYS` array in `worktime.js`. Use `YYYY-MM-DD`. Holidays are year-specific; add a new year explicitly.
+Edit `holidaysForYear` in `worktime.js`. Holidays are computed for each year in the selected range (do not keep a per-year date list):
+
+- LFT: 1 January, first Monday of February, third Monday of March, 1 May, 16 September, third Monday of November, 25 December
+- Holy Thursday and Good Friday (Easter minus 3 and 2 days)
+- 1 October on presidential inauguration years (every six years from 2024)
+
+A full 2026 calendar year must be 252 working days / **2016** hours. 2088 hours means weekdays were counted and holidays were not subtracted.
 
 ### Change hours per day
 
@@ -53,6 +59,7 @@ Edit `HOURS_PER_DAY` in `worktime.js`.
 - Invalid hours/minutes (minutes over 59) and start-after-end must show an error, not silent zeros.
 - Relative asset paths only (`styles.css`, not `/styles.css`) so the project Pages URL works.
 - Do not reintroduce a MAUI/XAML app unless explicitly requested.
+- 2088 hours for a full year means holidays were not applied (261 weekdays × 8). The correct total with the current holiday rules is 2016.
 
 ## Out of scope (unless explicitly requested)
 
diff --git a/README.md b/README.md
index 67421da..b69bf34 100644
--- a/README.md
+++ b/README.md
@@ -32,23 +32,20 @@ Alternative: **Deploy from a branch** → `main` → `/` (root). Asset paths are
 ## Rules
 
 - Date range is **inclusive**.
-- A working day is Monday–Friday and **not** in `HOLIDAYS` (`worktime.js`).
-- Expected hours = `8 × working days` (the main result).
+- A working day is Monday–Friday minus holidays computed for the years in the range (`holidaysForYear` in `worktime.js`).
+- Expected hours = `8 × working days` (the main result). A full 2026 year is **2016:00** (252 days), not 2088:00 (261 weekdays with no holidays).
 - Difference = hours worked − expected (minus sign and red when behind).
 - Daily average = worked ÷ working days (`—` if there are no working days).
 - Time format: results use `h:mm` with two-digit minutes. Input is two numeric fields (hours and minutes), so Android can use the number keypad.
 
-Holidays are year-specific (Mexican federal holidays plus Holy Thursday and Good Friday):
+Holidays follow Mexican LFT rules (fixed dates and movable Mondays) plus Holy Thursday and Good Friday, generated for each year in the range. 2026 dates:
 
 ```
-2025-01-01  2025-02-03  2025-03-17  2025-04-17  2025-04-18
-2025-05-01  2025-09-16  2025-11-18  2025-12-25
-
 2026-01-01  2026-02-02  2026-03-16  2026-04-02  2026-04-03
 2026-05-01  2026-09-16  2026-11-16  2026-12-25
 ```
 
-Add more ISO dates (`YYYY-MM-DD`) to `HOLIDAYS` in `worktime.js`. Change hours per day with `HOURS_PER_DAY` in the same file.
+Change hours per day with `HOURS_PER_DAY` in `worktime.js`.
 
 ## Files
 
diff --git a/app.js b/app.js
index cb86587..5ec6389 100644
--- a/app.js
+++ b/app.js
@@ -11,6 +11,7 @@
   var expectedEl = document.getElementById("expected-hours");
   var differenceEl = document.getElementById("hours-difference");
   var dailyEl = document.getElementById("daily-hours");
+  var holidayNoteEl = document.getElementById("holiday-note");
 
   function todayIso() {
     var now = new Date();
@@ -31,12 +32,55 @@
     if (!minutesInput.value) minutesInput.value = "0";
   }
 
+  var MONTHS_SHORT = [
+    "ene",
+    "feb",
+    "mar",
+    "abr",
+    "may",
+    "jun",
+    "jul",
+    "ago",
+    "sep",
+    "oct",
+    "nov",
+    "dic",
+  ];
+
+  function holidayLabel(iso) {
+    var parts = iso.split("-");
+    var d = Number(parts[2]);
+    var month = MONTHS_SHORT[Number(parts[1]) - 1];
+    return d + " " + month;
+  }
+
+  function updateHolidayNote(startIso, endIso) {
+    if (!holidayNoteEl || !Worktime.holidaysForRange) return;
+    var startYear = Number(String(startIso).slice(0, 4));
+    var endYear = Number(String(endIso).slice(0, 4));
+    if (!startYear) {
+      holidayNoteEl.textContent = "Los festivos se calculan para el año del rango.";
+      return;
+    }
+    var year = startYear;
+    var list = Worktime.holidaysForYear(year);
+    var labels = [];
+    for (var i = 0; i < list.length; i++) labels.push(holidayLabel(list[i]));
+    var extra =
+      endYear && endYear !== startYear
+        ? " El rango cruza de " + startYear + " a " + endYear + "."
+        : "";
+    holidayNoteEl.textContent =
+      "Festivos " + year + ": " + labels.join(", ") + "." + extra;
+  }
+
   function showError(message) {
     errorEl.hidden = !message;
     errorEl.textContent = message || "";
   }
 
   function render() {
+    updateHolidayNote(startInput.value, endInput.value);
     var parts = Worktime.parseDurationParts(hoursInput.value, minutesInput.value);
     var result = Worktime.calculate(
       startInput.value,
@@ -81,7 +125,9 @@
   });
 
   startInput.addEventListener("change", render);
+  startInput.addEventListener("input", render);
   endInput.addEventListener("change", render);
+  endInput.addEventListener("input", render);
   hoursInput.addEventListener("input", render);
   hoursInput.addEventListener("change", render);
   minutesInput.addEventListener("input", render);
diff --git a/index.html b/index.html
index 3e6466e..286b249 100644
--- a/index.html
+++ b/index.html
@@ -82,10 +82,8 @@ <h1>Horas laborales</h1>
             <dd id="daily-hours">0:00</dd>
           </div>
         </dl>
-        <p class="note">
-          Festivos 2026: 1 ene, 2 feb, 16 mar, 2–3 abr, 1 may, 16 sep, 16 nov,
-          25 dic. También hay fechas de 2025. Edita la lista en
-          <code>worktime.js</code>.
+        <p class="note" id="holiday-note">
+          Festivos oficiales (LFT) y Jueves/Viernes Santo del año del rango.
         </p>
       </section>
 
@@ -96,7 +94,7 @@ <h1>Horas laborales</h1>
       </footer>
     </main>
 
-    <script src="worktime.js"></script>
-    <script src="app.js"></script>
+    <script src="worktime.js?v=2026-08-26-year"></script>
+    <script src="app.js?v=2026-08-26-year"></script>
   </body>
 </html>
diff --git a/worktime.js b/worktime.js
index 64a5b01..0f20753 100644
--- a/worktime.js
+++ b/worktime.js
@@ -6,35 +6,15 @@
   "use strict";
 
   var HOURS_PER_DAY = 8;
-
-  // Year-specific Mexican federal holidays plus Holy Thursday and Good Friday.
-  var HOLIDAYS = [
-    "2025-01-01",
-    "2025-02-03",
-    "2025-03-17",
-    "2025-04-17",
-    "2025-04-18",
-    "2025-05-01",
-    "2025-09-16",
-    "2025-11-18",
-    "2025-12-25",
-    "2026-01-01",
-    "2026-02-02",
-    "2026-03-16",
-    "2026-04-02",
-    "2026-04-03",
-    "2026-05-01",
-    "2026-09-16",
-    "2026-11-16",
-    "2026-12-25",
-  ];
+  var MS_PER_DAY = 24 * 60 * 60 * 1000;
 
   function parseIsoDate(iso) {
-    var parts = String(iso).split("-");
-    if (parts.length !== 3) return null;
-    var y = Number(parts[0]);
-    var m = Number(parts[1]);
-    var d = Number(parts[2]);
+    var raw = String(iso == null ? "" : iso).trim();
+    var match = /^(\d{4})-(\d{2})-(\d{2})/.exec(raw);
+    if (!match) return null;
+    var y = Number(match[1]);
+    var m = Number(match[2]);
+    var d = Number(match[3]);
     if (!y || m < 1 || m > 12 || d < 1 || d > 31) return null;
     return Date.UTC(y, m - 1, d);
   }
@@ -43,6 +23,66 @@
     return new Date(utcMs).toISOString().slice(0, 10);
   }
 
+  /** n-th Monday of a month (monthIndex 0–11). */
+  function nthMonday(year, monthIndex, n) {
+    var firstDow = new Date(Date.UTC(year, monthIndex, 1)).getUTCDay();
+    var offset = (1 - firstDow + 7) % 7;
+    return toIsoDate(Date.UTC(year, monthIndex, 1 + offset + (n - 1) * 7));
+  }
+
+  /** Easter Sunday (Anonymous Gregorian algorithm), UTC midnight. */
+  function easterSundayUtc(year) {
+    var a = year % 19;
+    var b = Math.floor(year / 100);
+    var c = year % 100;
+    var d = Math.floor(b / 4);
+    var e = b % 4;
+    var f = Math.floor((b + 8) / 25);
+    var g = Math.floor((b - f + 1) / 3);
+    var h = (19 * a + b - d - g + 15) % 30;
+    var i = Math.floor(c / 4);
+    var k = c % 4;
+    var l = (32 + 2 * e + 2 * i - h - k) % 7;
+    var m = Math.floor((a + 11 * h + 22 * l) / 451);
+    var month = Math.floor((h + l - 7 * m + 114) / 31);
+    var day = ((h + l - 7 * m + 114) % 31) + 1;
+    return Date.UTC(year, month - 1, day);
+  }
+
+  /**
+   * Mexican LFT rest days for a calendar year, plus Holy Thursday and Good Friday.
+   * Presidential inauguration (1 Oct every six years from 2024) is included when it applies.
+   */
+  function holidaysForYear(year) {
+    var easter = easterSundayUtc(year);
+    var list = [
+      toIsoDate(Date.UTC(year, 0, 1)),
+      nthMonday(year, 1, 1),
+      nthMonday(year, 2, 3),
+      toIsoDate(easter - 3 * MS_PER_DAY),
+      toIsoDate(easter - 2 * MS_PER_DAY),
+      toIsoDate(Date.UTC(year, 4, 1)),
+      toIsoDate(Date.UTC(year, 8, 16)),
+      nthMonday(year, 10, 3),
+      toIsoDate(Date.UTC(year, 11, 25)),
+    ];
+    if (year >= 2024 && (year - 2024) % 6 === 0) {
+      list.push(toIsoDate(Date.UTC(year, 9, 1)));
+    }
+    return list;
+  }
+
+  function holidaysForRange(startIso, endIso) {
+    var startYear = Number(String(startIso).slice(0, 4));
+    var endYear = Number(String(endIso).slice(0, 4));
+    if (!startYear || !endYear || startYear > endYear) return [];
+    var list = [];
+    for (var y = startYear; y <= endYear; y++) {
+      list = list.concat(holidaysForYear(y));
+    }
+    return list;
+  }
+
   function countWorkingDays(startIso, endIso, holidays) {
     var start = parseIsoDate(startIso);
     var end = parseIsoDate(endIso);
@@ -50,11 +90,11 @@
     if (start > end) return null;
 
     var holidaySet = {};
-    var list = holidays || HOLIDAYS;
+    var list = holidays != null ? holidays : holidaysForRange(startIso, endIso);
     for (var i = 0; i < list.length; i++) holidaySet[list[i]] = true;
 
     var days = 0;
-    for (var t = start; t <= end; t += 24 * 60 * 60 * 1000) {
+    for (var t = start; t <= end; t += MS_PER_DAY) {
       var iso = toIsoDate(t);
       var dow = new Date(t).getUTCDay(); // 0 Sun … 6 Sat
       if (dow === 0 || dow === 6 || holidaySet[iso]) continue;
@@ -125,7 +165,8 @@
 
   var api = {
     HOURS_PER_DAY: HOURS_PER_DAY,
-    HOLIDAYS: HOLIDAYS,
+    holidaysForYear: holidaysForYear,
+    holidaysForRange: holidaysForRange,
     parseIsoDate: parseIsoDate,
     countWorkingDays: countWorkingDays,
     expectedHours: expectedHours,
diff --git a/worktime.test.js b/worktime.test.js
index e0f271a..4fb2855 100644
--- a/worktime.test.js
+++ b/worktime.test.js
@@ -58,6 +58,33 @@ test("Nov 16 2026 (Mon holiday) is excluded", () => {
   assert.equal(W.countWorkingDays("2026-11-16", "2026-11-16"), 0);
 });
 
+test("full year 2026 is 252 working days / 2016 hours, not 261 / 2088", () => {
+  assert.equal(W.countWorkingDays("2026-01-01", "2026-12-31"), 252);
+  assert.equal(W.expectedHours("2026-01-01", "2026-12-31"), 2016);
+  assert.equal(W.formatHmm(W.expectedHours("2026-01-01", "2026-12-31")), "2016:00");
+  assert.equal(W.countWorkingDays("2026-01-01", "2026-12-31", []), 261);
+  assert.equal(W.expectedHours("2026-01-01", "2026-12-31", [], 8), 2088);
+});
+
+test("full year 2025 is also 252 working days / 2016 hours", () => {
+  assert.equal(W.countWorkingDays("2025-01-01", "2025-12-31"), 252);
+  assert.equal(W.expectedHours("2025-01-01", "2025-12-31"), 2016);
+});
+
+test("2026 holidays follow LFT Mondays plus Holy Week", () => {
+  assert.deepEqual(W.holidaysForYear(2026), [
+    "2026-01-01",
+    "2026-02-02",
+    "2026-03-16",
+    "2026-04-02",
+    "2026-04-03",
+    "2026-05-01",
+    "2026-09-16",
+    "2026-11-16",
+    "2026-12-25",
+  ]);
+});
+
 test("start after end is invalid", () => {
   assert.equal(W.countWorkingDays("2025-02-01", "2025-01-01"), null);
   const r = W.calculate("2025-02-01", "2025-01-01", "8:00");