diff --git a/taxes_az/taxes_az/doctype/property_tax_return/property_tax_return.js b/taxes_az/taxes_az/doctype/property_tax_return/property_tax_return.js
index b774761..cb5a035 100644
--- a/taxes_az/taxes_az/doctype/property_tax_return/property_tax_return.js
+++ b/taxes_az/taxes_az/doctype/property_tax_return/property_tax_return.js
@@ -50,6 +50,9 @@ frappe.ui.form.on('Property tax return', {
 
 		// Validate minimum asset values
 		validate_minimum_asset_value(frm);
+
+		// Calculate 509.2 on load
+		calculate_509_2(frm);
 	},
 
 	// Handle year changes
@@ -57,6 +60,7 @@ frappe.ui.form.on('Property tax return', {
 		if (frm.doc.il && (frm.doc.tam_il || frm.doc.il_erzinde)) {
 			reload_property_tax_data(frm);
 		}
+		calculate_509_2(frm);
 	},
 
 	// Checkbox handlers - ensure mutual exclusivity
@@ -71,6 +75,9 @@ frappe.ui.form.on('Property tax return', {
 			// Clear warnings when switching to tam_il
 			validate_minimum_asset_value(frm);
 
+			// Calculate 509.2
+			calculate_509_2(frm);
+
 			if (frm.doc.il) {
 				reload_property_tax_data(frm);
 			}
@@ -91,6 +98,9 @@ frappe.ui.form.on('Property tax return', {
 			// Validate when checking il_erzinde
 			validate_minimum_asset_value(frm);
 
+			// Calculate 509.2
+			calculate_509_2(frm);
+
 			if (frm.doc.il) {
 				reload_property_tax_data(frm);
 			}
@@ -100,6 +110,7 @@ frappe.ui.form.on('Property tax return', {
 		} else {
 			// Clear warnings when unchecking il_erzinde
 			validate_minimum_asset_value(frm);
+			calculate_509_2(frm);
 		}
 	},
 
@@ -427,6 +438,9 @@ function reload_property_tax_data(frm) {
 
 				frm.refresh_fields();
 
+				// Calculate 509.2 after data reload
+				calculate_509_2(frm);
+
 				frappe.show_alert({
 					message: __('Property tax data loaded successfully'),
 					indicator: 'green'
@@ -737,6 +751,50 @@ function highlight_invalid_cells(frm, invalid_rows_1, invalid_rows_2) {
 
 // ==================== END VALIDATION ====================
 
+// ==================== FORMULA 509.2 CALCULATION ====================
+// Calculate field 509.2 based on formula: ((503.1 + 504.1) / 24 * 507) * 1%
+
+function calculate_509_2(frm) {
+	// Only calculate when il_erzinde is checked
+	if (!frm.doc.il_erzinde) {
+		return;
+	}
+
+	// Get value from field 507 (ayla from vergi_hesab_4cu_1 first row)
+	let value_507 = 0;
+	if (frm.doc.vergi_hesab_4cu_1 && frm.doc.vergi_hesab_4cu_1.length > 0) {
+		value_507 = flt(frm.doc.vergi_hesab_4cu_1[0].ayla);
+	}
+
+	// Get value from field 503.1 (manatla from vergi_hesab_1ci_1)
+	let value_503_1 = 0;
+	(frm.doc.vergi_hesab_1ci_1 || []).forEach(row => {
+		if (row.göstəricilər && row.göstəricilər.startsWith('503.1')) {
+			value_503_1 = flt(row.manatla);
+		}
+	});
+
+	// Get value from field 504.1 (manatla from vergi_hesab_2ci)
+	let value_504_1 = 0;
+	(frm.doc.vergi_hesab_2ci || []).forEach(row => {
+		if (row.göstəricilər && row.göstəricilər.startsWith('504.1')) {
+			value_504_1 = flt(row.manatla);
+		}
+	});
+
+	// Calculate: ((503.1 + 504.1) / 24 * 507) * 1%
+	let result = ((value_503_1 + value_504_1) / 24 * value_507) * 0.01;
+
+	// Set value to field 509.2 (manatla in vergi_hesab_5ci)
+	(frm.doc.vergi_hesab_5ci || []).forEach(row => {
+		if (row.göstəricilər && row.göstəricilər.startsWith('509.2')) {
+			frappe.model.set_value(row.doctype, row.name, 'manatla', result);
+		}
+	});
+}
+
+// ==================== END FORMULA 509.2 ====================
+
 // Обработчики для дочерней таблицы Elave 2 - автоматический пересчет суммы binalar
 frappe.ui.form.on('Property tax return Elave 2', {
 	form_render: function(frm, cdt, cdn) {
@@ -803,4 +861,27 @@ frappe.ui.form.on('Property tax return Elave 1', {
 	elave_1_remove: function(frm, cdt, cdn) {
 		calculate_elave_1_totals(frm);
 	}
+});
+
+// ==================== CHILD TABLE EVENT HANDLERS FOR 509.2 FORMULA ====================
+
+// Event handler for vergi_hesab_4cu_1 changes (field 507)
+frappe.ui.form.on('Property tax return Emlak vergi hesablamasi 4cu cedvel 1', {
+	ayla: function(frm, cdt, cdn) {
+		calculate_509_2(frm);
+	}
+});
+
+// Event handler for vergi_hesab_1ci_1 changes (field 503.1)
+frappe.ui.form.on('Property tax return Emlak vergi hesablamasi 1ci cedvel 1', {
+	manatla: function(frm, cdt, cdn) {
+		calculate_509_2(frm);
+	}
+});
+
+// Event handler for vergi_hesab_2ci changes (field 504.1)
+frappe.ui.form.on('Property tax return Emlak vergi hesablamasi 2ci cedvel', {
+	manatla: function(frm, cdt, cdn) {
+		calculate_509_2(frm);
+	}
 });
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