refactor: query meta data only once
diff --git a/erpnext/regional/report/datev/datev.py b/erpnext/regional/report/datev/datev.py
index a8e40cc..02296a9 100644
--- a/erpnext/regional/report/datev/datev.py
+++ b/erpnext/regional/report/datev/datev.py
@@ -8,17 +8,18 @@
   all required columns. Used to import the data into the DATEV Software.
 """
 from __future__ import unicode_literals
+
 import datetime
 import json
-import zlib
 import zipfile
 import six
+import frappe
+import pandas as pd
+
+from frappe import _
 from csv import QUOTE_NONNUMERIC
 from six import BytesIO
 from six import string_types
-import frappe
-from frappe import _
-import pandas as pd
 from .datev_constants import DataCategory
 from .datev_constants import Transactions
 from .datev_constants import DebtorsCreditors
@@ -287,9 +288,7 @@
 
 
 def get_header(filters, csv_class):
-	coa = frappe.get_value("Company", filters.get("company"), "chart_of_accounts")
-	description = filters.get("voucher_type", csv_class.FORMAT_NAME)
-	coa_used = "04" if "SKR04" in coa else ("03" if "SKR03" in coa else "")
+	description = filters.get('voucher_type', csv_class.FORMAT_NAME)
 
 	header = [
 		# DATEV format
@@ -316,13 +315,13 @@
 		# J = Imported by -- stays empty
 		'',
 		# K = Tax consultant number (Beraternummer)
-		frappe.get_value("DATEV Settings", filters.get("company"), "consultant_number"),
+		filters.get('consultant_number', '0000000'),
 		# L = Tax client number (Mandantennummer)
-		frappe.get_value("DATEV Settings", filters.get("company"), "client_number"),
+		filters.get('client_number', '00000'),
 		# M = Start of the fiscal year (Wirtschaftsjahresbeginn)
 		frappe.utils.formatdate(frappe.defaults.get_user_default("year_start_date"), "yyyyMMdd"),
 		# N = Length of account numbers (Sachkontenlänge)
-		'4',
+		'%d' % filters.get('acc_len', 4),
 		# O = Transaction batch start date (YYYYMMDD)
 		frappe.utils.formatdate(filters.get('from_date'), "yyyyMMdd"),
 		# P = Transaction batch end date (YYYYMMDD)
@@ -348,7 +347,7 @@
 		# TODO: Filter by Accounting Period. In export for closed Accounting Period, this will be "1"
 		'0',
 		# V = Default currency, for example, "EUR"
-		'"%s"' % frappe.get_value("Company", filters.get("company"), "default_currency"),
+		'"%s"' % filters.get('default_currency', 'EUR'),
 		# reserviert
 		'',
 		# Derivatskennzeichen
@@ -358,7 +357,7 @@
 		# reserviert
 		'',
 		# SKR
-		'"%s"' % coa_used,
+		'"%s"' % filters.get('skr', '04'),
 		# Branchen-Lösungs-ID
 		'',
 		# reserviert
@@ -389,6 +388,18 @@
 
 	validate(filters)
 
+	# set chart of accounts used
+	coa = frappe.get_value('Company', filters.get('company'), 'chart_of_accounts')
+	filters['skr'] = '04' if 'SKR04' in coa else ('03' if 'SKR03' in coa else '')
+
+	# set account number length
+	account_numbers = frappe.get_list('Account', fields=['account_number'], filters={'is_group': 0, 'account_number': ('!=', '')})
+	filters['acc_len'] = max([len(a.account_number) for a in account_numbers])
+
+	filters['consultant_number'] = frappe.get_value('DATEV Settings', filters.get('company'), 'consultant_number')
+	filters['client_number'] = frappe.get_value('DATEV Settings', filters.get('company'), 'client_number')
+	filters['default_currency'] = frappe.get_value('Company', filters.get('company'), 'default_currency')
+
 	# This is where my zip will be written
 	zip_buffer = BytesIO()
 	# This is my zip file