diff --git a/default_thai_company/fixtures/address_template.json b/default_thai_company/fixtures/address_template.json
new file mode 100644
index 0000000..fc0a8eb
--- /dev/null
+++ b/default_thai_company/fixtures/address_template.json
@@ -0,0 +1,11 @@
+[
+ {
+  "country": "Thailand",
+  "docstatus": 0,
+  "doctype": "Address Template",
+  "is_default": 1,
+  "modified": "2026-09-09 17:23:33.559202",
+  "name": "Thailand",
+  "template": "{{ address_line1 }}{% if address_line2 %} {{ address_line2 }}{% endif %}<br>\n{% if county %}{{ county }} {% endif -%}{{ city }}{% if state %} {{ state }}{% endif -%}{% if pincode %} {{ pincode }}{% endif -%}{% if country != \"Thailand\" %} {{ country }}{% endif %}<br>\n{% if phone or fax or email_id %}<br>{% endif -%}\n{% if phone %}{{ _(\"Phone\") }}: {{ phone }}<br>{% endif -%}\n{% if fax %}{{ _(\"Fax\") }}: {{ fax }}<br>{% endif -%}\n{% if email_id %}{{ _(\"Email\") }}: {{ email_id }}<br>{% endif -%}\n"
+ }
+]
diff --git a/default_thai_company/fixtures/letter_head.json b/default_thai_company/fixtures/letter_head.json
new file mode 100644
index 0000000..d3e1ee3
--- /dev/null
+++ b/default_thai_company/fixtures/letter_head.json
@@ -0,0 +1,25 @@
+[
+ {
+  "align": "Left",
+  "content": "<style>\n    .bpt-title {\n        display: -webkit-box;\n        display: flex;\n        -webkit-box-align: center;\n        align-items: center;\n        width: 100%;\n    }\n    .bpt-title img {\n        margin-right: 1em;\n    }\n    .bpt-title .bpt-company {\n        -webkit-box-flex: 1;\n        flex: 1;\n        text-align: right;\n    }\n</style>\n{% set company = get_letter_head_company(doc) %}\n{% if company %}\n<div class=\"bpt-title\">\n    {% if company.company_logo %}\n    <img alt=\"{{ company.company_name }}\" height=\"125\" src=\"{{ company.company_logo }}\">\n    {% endif %}\n    <div class=\"bpt-company\">\n        <h1>{{ company.company_name }}</h1>\n        <small>\n            {% if company.tax_id %}<div>Tax ID: {{ company.tax_id }}</div>{% endif %}\n            {% if company.address %}<div>{{ company.address }}</div>{% endif %}\n            {% if company.phone_no %}<div>Phone: {{ company.phone_no }}</div>{% endif %}\n            {% if company.email %}<div>Email: {{ company.email }}</div>{% endif %}\n        </small>\n    </div>\n</div>\n{% endif %}\n",
+  "disabled": 0,
+  "docstatus": 0,
+  "doctype": "Letter Head",
+  "footer": null,
+  "footer_align": "Left",
+  "footer_image": null,
+  "footer_image_height": 0.0,
+  "footer_image_width": 0.0,
+  "footer_script": null,
+  "footer_source": "HTML",
+  "header_script": null,
+  "image": null,
+  "image_height": 0.0,
+  "image_width": 0.0,
+  "is_default": 1,
+  "letter_head_name": "Default Letter Head",
+  "modified": "2026-09-10 09:51:23.933752",
+  "name": "Default Letter Head",
+  "source": "HTML"
+ }
+]
diff --git a/default_thai_company/hooks.py b/default_thai_company/hooks.py
index 22adbe7..38648fc 100644
--- a/default_thai_company/hooks.py
+++ b/default_thai_company/hooks.py
@@ -8,7 +8,7 @@ app_license = "gpl-3.0"
 # Apps
 # ------------------
 
-# required_apps = []
+required_apps = ["erpnext"]
 
 # Each item in the list will be shown as an app in the apps page
 # add_to_apps_screen = [
@@ -74,10 +74,17 @@ app_license = "gpl-3.0"
 # ----------
 
 # add methods and filters to jinja environment
-# jinja = {
-# 	"methods": "default_thai_company.utils.jinja_methods",
-# 	"filters": "default_thai_company.utils.jinja_filters"
-# }
+jinja = {
+	"methods": ["default_thai_company.utils.get_letter_head_company"],
+}
+
+# Fixtures
+# --------
+
+fixtures = [
+	{"doctype": "Letter Head", "filters": [["name", "in", ["Default Letter Head"]]]},
+	{"doctype": "Address Template", "filters": [["name", "in", ["Thailand"]]]},
+]
 
 # Installation
 # ------------
@@ -137,13 +144,12 @@ app_license = "gpl-3.0"
 # ---------------
 # Hook on document methods and events
 
-# doc_events = {
-# 	"*": {
-# 		"on_update": "method",
-# 		"on_cancel": "method",
-# 		"on_trash": "method"
-# 	}
-# }
+doc_events = {
+	"Letter Head": {
+		"before_import": "default_thai_company.utils.stash_letter_head_source",
+		"before_insert": "default_thai_company.utils.restore_letter_head_source",
+	}
+}
 
 # Scheduled Tasks
 # ---------------
@@ -246,4 +252,3 @@ app_license = "gpl-3.0"
 # ------------
 # List of apps whose translatable strings should be excluded from this app's translations.
 # ignore_translatable_strings_from = []
-
diff --git a/default_thai_company/utils.py b/default_thai_company/utils.py
new file mode 100644
index 0000000..84da132
--- /dev/null
+++ b/default_thai_company/utils.py
@@ -0,0 +1,40 @@
+import frappe
+from erpnext import get_default_company
+from frappe.contacts.doctype.address.address import get_default_address, render_address
+
+
+def get_letter_head_company(doc=None):
+	"""Company details for the Letter Head template.
+
+	Resolves the company from the printed document's `company` field, falling
+	back to the user's/global default company for documents without one.
+	Returns None when no company can be resolved.
+	"""
+	company_name = (doc.get("company") if doc else None) or get_default_company()
+	if not company_name or not frappe.db.exists("Company", company_name):
+		return None
+
+	company = frappe.get_cached_doc("Company", company_name)
+	address_name = get_default_address("Company", company_name)
+
+	return frappe._dict(
+		name=company.name,
+		company_name=company.company_name,
+		tax_id=company.tax_id,
+		phone_no=company.phone_no,
+		email=company.email,
+		website=company.website,
+		company_logo=company.company_logo,
+		address=render_address(address_name, check_permissions=False) if address_name else None,
+	)
+
+
+def stash_letter_head_source(doc, method=None):
+	"""Fixture import re-inserts the Letter Head; remember the fixture's `source`."""
+	doc.flags.fixture_source = doc.source
+
+
+def restore_letter_head_source(doc, method=None):
+	"""LetterHead.before_insert forces `source = "Image"`; restore the fixture's value."""
+	if doc.flags.fixture_source:
+		doc.source = doc.flags.fixture_source