diff --git a/taxes_az/taxes_az/doctype/tax_article/tax_article.js b/taxes_az/taxes_az/doctype/tax_article/tax_article.js
index f5398cc..9e6f0fc 100644
--- a/taxes_az/taxes_az/doctype/tax_article/tax_article.js
+++ b/taxes_az/taxes_az/doctype/tax_article/tax_article.js
@@ -1,8 +1,120 @@
-// Copyright (c) 2025, Jey Soft and contributors
-// For license information, please see license.txt
+frappe.ui.form.on('Tax Article', {
+    // Инициализация: сохраняем начальные значения
+    refresh: function(frm) {
+        store_last_values(frm);
+    },
+    
+    // При изменении date_from
+    date_from: function(frm) {
+        if (!frm._is_calculating) {
+            frm._is_calculating = true;
+            
+            if (frm.doc.date_from && frm.doc.date_to) {
+                // Если есть date_to, всегда пересчитываем duration
+                calculate_duration(frm);
+                
+                // Валидация
+                validate_dates(frm);
+            }
+            
+            store_last_values(frm);
+            frm._is_calculating = false;
+        }
+    },
+    
+    // При изменении date_to
+    date_to: function(frm) {
+        if (!frm._is_calculating) {
+            frm._is_calculating = true;
+            
+            if (frm.doc.date_to && frm.doc.date_from) {
+                // Валидация
+                if (validate_dates(frm)) {
+                    // Пересчитываем duration
+                    calculate_duration(frm);
+                }
+            }
+            
+            store_last_values(frm);
+            frm._is_calculating = false;
+        }
+    },
+    
+    // При изменении duration
+    duration: function(frm) {
+        if (!frm._is_calculating) {
+            frm._is_calculating = true;
+            
+            if (frm.doc.duration && frm.doc.date_from) {
+                // Пересчитываем date_to
+                calculate_date_to(frm);
+                
+                // Валидация
+                validate_dates(frm);
+            }
+            
+            store_last_values(frm);
+            frm._is_calculating = false;
+        }
+    },
+    
+    // Валидация перед сохранением
+    validate: function(frm) {
+        if (frm.doc.date_from && frm.doc.date_to) {
+            validate_dates(frm);
+        }
+    }
+});
 
-// frappe.ui.form.on("Tax Article", {
-// 	refresh(frm) {
+// Рассчитать date_to на основе date_from и duration
+function calculate_date_to(frm) {
+    if (!frm.doc.date_from || !frm.doc.duration) return;
+    
+    let from_date = frappe.datetime.str_to_obj(frm.doc.date_from);
+    let to_date = new Date(from_date);
+    to_date.setFullYear(to_date.getFullYear() + frm.doc.duration);
+    
+    frm.set_value('date_to', frappe.datetime.obj_to_str(to_date));
+}
 
-// 	},
-// });
+// Рассчитать duration на основе date_from и date_to
+function calculate_duration(frm) {
+    if (!frm.doc.date_from || !frm.doc.date_to) return;
+    
+    let from_date = frappe.datetime.str_to_obj(frm.doc.date_from);
+    let to_date = frappe.datetime.str_to_obj(frm.doc.date_to);
+    
+    // Рассчитываем разницу в годах
+    let years = (to_date - from_date) / (365.25 * 24 * 60 * 60 * 1000);
+    let rounded_years = Math.round(years);
+    
+    frm.set_value('duration', rounded_years);
+}
+
+// Валидация: date_to должна быть >= date_from
+function validate_dates(frm) {
+    if (!frm.doc.date_from || !frm.doc.date_to) return true;
+    
+    let from_date = frappe.datetime.str_to_obj(frm.doc.date_from);
+    let to_date = frappe.datetime.str_to_obj(frm.doc.date_to);
+    
+    if (to_date < from_date) {
+        frappe.msgprint({
+            title: __('Invalid Date Range'),
+            indicator: 'red',
+            message: __('Date To cannot be earlier than Date From')
+        });
+        return false;
+    }
+    
+    return true;
+}
+
+// Сохранить текущие значения полей
+function store_last_values(frm) {
+    frm._last_values = {
+        date_from: frm.doc.date_from,
+        date_to: frm.doc.date_to,
+        duration: frm.doc.duration
+    };
+}
\ No newline at end of file
diff --git a/taxes_az/taxes_az/doctype/tax_article/tax_article.json b/taxes_az/taxes_az/doctype/tax_article/tax_article.json
index a34bbe4..eeb1851 100644
--- a/taxes_az/taxes_az/doctype/tax_article/tax_article.json
+++ b/taxes_az/taxes_az/doctype/tax_article/tax_article.json
@@ -14,7 +14,12 @@
   "lft",
   "rgt",
   "is_group",
-  "old_parent"
+  "old_parent",
+  "validity_period",
+  "date_from",
+  "duration",
+  "column_break_zcwq",
+  "date_to"
  ],
  "fields": [
   {
@@ -27,8 +32,7 @@
    "fieldtype": "Text",
    "in_list_view": 1,
    "label": "Article Name",
-   "reqd": 1,
-   "unique": 1
+   "reqd": 1
   },
   {
    "description": "Declaration text for tax article",
@@ -45,19 +49,19 @@
   {
    "fieldname": "lft",
    "fieldtype": "Float",
-   "precision": "2",
    "hidden": 1,
    "label": "Left",
    "no_copy": 1,
+   "precision": "2",
    "read_only": 1
   },
   {
    "fieldname": "rgt",
    "fieldtype": "Float",
-   "precision": "2",
    "hidden": 1,
    "label": "Right",
    "no_copy": 1,
+   "precision": "2",
    "read_only": 1
   },
   {
@@ -72,12 +76,36 @@
    "ignore_user_permissions": 1,
    "label": "Parent Tax Article",
    "options": "Tax Article"
+  },
+  {
+   "fieldname": "validity_period",
+   "fieldtype": "Section Break",
+   "label": "Validity Period"
+  },
+  {
+   "fieldname": "date_from",
+   "fieldtype": "Date",
+   "label": "Date From"
+  },
+  {
+   "fieldname": "duration",
+   "fieldtype": "Int",
+   "label": "Duration"
+  },
+  {
+   "fieldname": "column_break_zcwq",
+   "fieldtype": "Column Break"
+  },
+  {
+   "fieldname": "date_to",
+   "fieldtype": "Date",
+   "label": "Date To"
   }
  ],
  "index_web_pages_for_search": 1,
  "is_tree": 1,
  "links": [],
- "modified": "2025-08-26 19:56:54.264329",
+ "modified": "2025-10-31 17:17:26.936793",
  "modified_by": "Administrator",
  "module": "Taxes Az",
  "name": "Tax Article",
@@ -98,7 +126,8 @@
    "write": 1
   }
  ],
+ "row_format": "Dynamic",
  "sort_field": "creation",
  "sort_order": "DESC",
  "states": []
-}
\ No newline at end of file
+}
diff --git a/taxes_az/taxes_az/doctype/tax_article/tax_article.py b/taxes_az/taxes_az/doctype/tax_article/tax_article.py
index 3f9044f..4773321 100644
--- a/taxes_az/taxes_az/doctype/tax_article/tax_article.py
+++ b/taxes_az/taxes_az/doctype/tax_article/tax_article.py
@@ -1,8 +1,17 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2025, Your Company and contributors
+# For license information, please see license.txt
+
+from __future__ import unicode_literals
 import frappe
 from frappe.model.document import Document
+from frappe.utils import getdate, add_years
 
 class TaxArticle(Document):
     def autoname(self):
+        """
+        Auto-generate document name from article_name
+        """
         if not self.article_name:
             return
             
@@ -21,4 +30,45 @@ class TaxArticle(Document):
             name = original_name[:max_length] + suffix
             counter += 1
         
-        self.name = name
\ No newline at end of file
+        self.name = name
+    
+    def validate(self):
+        """
+        Validate Tax Article fields and auto-calculate missing values
+        """
+        # Автоматический расчет полей
+        self.auto_calculate_validity_fields()
+        
+        # Валидация дат
+        self.validate_date_range()
+    
+    def auto_calculate_validity_fields(self):
+        """
+        Auto-calculate missing validity fields based on available data
+        """
+        # Если есть date_from и duration, но нет date_to
+        if self.date_from and self.duration and not self.date_to:
+            self.date_to = add_years(getdate(self.date_from), self.duration)
+        
+        # Если есть date_from и date_to, но нет duration
+        elif self.date_from and self.date_to and not self.duration:
+            from_date = getdate(self.date_from)
+            to_date = getdate(self.date_to)
+            
+            # Рассчитываем разницу в годах
+            years = (to_date - from_date).days / 365.25
+            self.duration = round(years)
+    
+    def validate_date_range(self):
+        """
+        Validate that date_to is not earlier than date_from
+        """
+        if self.date_from and self.date_to:
+            from_date = getdate(self.date_from)
+            to_date = getdate(self.date_to)
+            
+            if to_date < from_date:
+                frappe.throw(
+                    frappe._("Date To cannot be earlier than Date From"),
+                    title=frappe._("Invalid Date Range")
+                )
\ No newline at end of file