diff --git a/erpnext/accounts/deferred_revenue.py b/erpnext/accounts/deferred_revenue.py
index e638fc7..e146ae9 100644
--- a/erpnext/accounts/deferred_revenue.py
+++ b/erpnext/accounts/deferred_revenue.py
@@ -2,9 +2,9 @@
 
 import frappe
 from frappe import _
-from frappe.utils import date_diff, add_months, today, getdate, add_days, flt
+from frappe.utils import date_diff, add_months, today, getdate, add_days, flt, get_last_day
 from erpnext.accounts.utils import get_account_currency
-from erpnext.accounts.general_ledger import make_gl_entries
+from frappe.email import sendmail_to_system_managers
 
 def validate_service_stop_date(doc):
 	''' Validates service_stop_date for Purchase Invoice and Sales Invoice '''
@@ -33,47 +33,49 @@
 			frappe.throw(_("Cannot change Service Stop Date for item in row {0}".format(item.idx)))
 
 def convert_deferred_expense_to_expense(start_date=None, end_date=None):
+	# book the expense/income on the last day, but it will be trigger on the 1st of month at 12:00 AM
+	if not start_date:
+		start_date = add_months(today(), -1)
+	if not end_date:
+		end_date = add_days(today(), -1)
+
 	# check for the purchase invoice for which GL entries has to be done
 	invoices = frappe.db.sql_list('''
-		select distinct parent from `tabPurchase Invoice Item` where service_start_date<=%s and service_end_date>=%s
+		select distinct parent from `tabPurchase Invoice Item`
+		where service_start_date<=%s and service_end_date>=%s
 		and enable_deferred_expense = 1 and docstatus = 1 and ifnull(amount, 0) > 0
-	''', (end_date or today(), start_date or add_months(today(), -1)))
+	''', (end_date, start_date))
 
 	# For each invoice, book deferred expense
 	for invoice in invoices:
 		doc = frappe.get_doc("Purchase Invoice", invoice)
-		book_deferred_income_or_expense(doc, start_date, end_date)
+		book_deferred_income_or_expense(doc, end_date)
 
 def convert_deferred_revenue_to_income(start_date=None, end_date=None):
+	# book the expense/income on the last day, but it will be trigger on the 1st of month at 12:00 AM
+	if not start_date:
+		start_date = add_months(today(), -1)
+	if not end_date:
+		end_date = add_days(today(), -1)
+
 	# check for the sales invoice for which GL entries has to be done
 	invoices = frappe.db.sql_list('''
-		select distinct parent from `tabSales Invoice Item` where service_start_date<=%s and service_end_date>=%s
+		select distinct parent from `tabSales Invoice Item`
+		where service_start_date<=%s and service_end_date>=%s
 		and enable_deferred_revenue = 1 and docstatus = 1 and ifnull(amount, 0) > 0
-	''', (end_date or today(), start_date or add_months(today(), -1)))
+	''', (end_date, start_date))
 
-	# For each invoice, book deferred revenue
 	for invoice in invoices:
 		doc = frappe.get_doc("Sales Invoice", invoice)
-		book_deferred_income_or_expense(doc, start_date, end_date)
+		book_deferred_income_or_expense(doc, end_date)
 
-def get_booking_dates(doc, item, start_date=None, end_date=None):
+def get_booking_dates(doc, item, posting_date=None):
+	if not posting_date:
+		posting_date = add_days(today(), -1)
+
+	last_gl_entry = False
+
 	deferred_account = "deferred_revenue_account" if doc.doctype=="Sales Invoice" else "deferred_expense_account"
-	last_gl_entry, skip = False, False
-
-	booking_end_date = getdate(add_days(today(), -1) if not end_date else end_date)
-	if booking_end_date < item.service_start_date or \
-		(item.service_stop_date and booking_end_date.month > item.service_stop_date.month):
-		return None, None, None, True
-	elif booking_end_date >= item.service_end_date:
-		last_gl_entry = True
-		booking_end_date = item.service_end_date
-	elif item.service_stop_date and item.service_stop_date <= booking_end_date:
-		last_gl_entry = True
-		booking_end_date = item.service_stop_date
-
-	booking_start_date = getdate(add_months(today(), -1) if not start_date else start_date)
-	booking_start_date = booking_start_date \
-		if booking_start_date > item.service_start_date else item.service_start_date
 
 	prev_gl_entry = frappe.db.sql('''
 		select name, posting_date from `tabGL Entry` where company=%s and account=%s and
@@ -81,17 +83,28 @@
 		order by posting_date desc limit 1
 	''', (doc.company, item.get(deferred_account), doc.doctype, doc.name, item.name), as_dict=True)
 
-	if not prev_gl_entry and item.service_start_date < booking_start_date:
-		booking_start_date = item.service_start_date
-	elif prev_gl_entry:
-		booking_start_date = getdate(add_days(prev_gl_entry[0].posting_date, 1))
-		skip = True if booking_start_date > booking_end_date else False
+	if prev_gl_entry:
+		start_date = getdate(add_days(prev_gl_entry[0].posting_date, 1))
+	else:
+		start_date = item.service_start_date
 
-	return last_gl_entry, booking_start_date, booking_end_date, skip
+	end_date = get_last_day(start_date)
+	if end_date >= item.service_end_date:
+		end_date = item.service_end_date
+		last_gl_entry = True
+ 	elif item.service_stop_date and end_date >= item.service_stop_date:
+		 end_date = item.service_stop_date
+		 last_gl_entry = True
 
-def calculate_amount_and_base_amount(doc, item, last_gl_entry, total_days, total_booking_days):
-	account_currency = get_account_currency(item.expense_account)
+	if end_date > getdate(posting_date):
+		end_date = posting_date
 
+	if getdate(start_date) <= getdate(end_date):
+		return start_date, end_date, last_gl_entry
+	else:
+		return None, None, None
+
+def calculate_amount(doc, item, last_gl_entry, total_days, total_booking_days, account_currency):
 	if doc.doctype == "Sales Invoice":
 		total_credit_debit, total_credit_debit_currency = "debit", "debit_in_account_currency"
 		deferred_account = "deferred_revenue_account"
@@ -123,28 +136,16 @@
 
 	return amount, base_amount
 
-def book_deferred_income_or_expense(doc, start_date=None, end_date=None):
-	# book the expense/income on the last day, but it will be trigger on the 1st of month at 12:00 AM
-	# start_date: 1st of the last month or the start date
-	# end_date: end_date or today-1
+def book_deferred_income_or_expense(doc, posting_date=None):
 	enable_check = "enable_deferred_revenue" \
 		if doc.doctype=="Sales Invoice" else "enable_deferred_expense"
-
-	gl_entries = []
-	for item in doc.get('items'):
-		if not item.get(enable_check): continue
-
-		skip = False
-		last_gl_entry, booking_start_date, booking_end_date, skip = \
-			get_booking_dates(doc, item, start_date, end_date)
-
-		if skip: continue
-		total_days = date_diff(item.service_end_date, item.service_start_date) + 1
-		total_booking_days = date_diff(booking_end_date, booking_start_date) + 1
+	last_gl_entry = False
+	end_date = None
+	def _book_deferred_revenue_or_expense(item):
+		start_date, end_date, last_gl_entry = get_booking_dates(doc, item, posting_date=posting_date)
+		if not (start_date and end_date): return
 
 		account_currency = get_account_currency(item.expense_account)
-		amount, base_amount = calculate_amount_and_base_amount(doc, item, last_gl_entry, total_days, total_booking_days)
-
 		if doc.doctype == "Sales Invoice":
 			against, project = doc.customer, doc.project
 			credit_account, debit_account = item.income_account, item.deferred_revenue_account
@@ -152,36 +153,62 @@
 			against, project = doc.supplier, item.project
 			credit_account, debit_account = item.deferred_expense_account, item.expense_account
 
-		# GL Entry for crediting the amount in the deferred expense
-		gl_entries.append(
-			doc.get_gl_dict({
-				"account": credit_account,
-				"against": against,
-				"credit": base_amount,
-				"credit_in_account_currency": amount,
-				"cost_center": item.cost_center,
-				"voucher_detail_no": item.name,
-				'posting_date': booking_end_date,
-				'project': project
-			}, account_currency)
-		)
-		# GL Entry to debit the amount from the expense
-		gl_entries.append(
-			doc.get_gl_dict({
-				"account": debit_account,
-				"against": against,
-				"debit": base_amount,
-				"debit_in_account_currency": amount,
-				"cost_center": item.cost_center,
-				"voucher_detail_no": item.name,
-				'posting_date': booking_end_date,
-				'project': project
-			}, account_currency)
-		)
+		total_days = date_diff(item.service_end_date, item.service_start_date) + 1
+		total_booking_days = date_diff(end_date, start_date) + 1
+
+		amount, base_amount = calculate_amount(doc, item, last_gl_entry,
+			total_days, total_booking_days, account_currency)
+
+		make_gl_entries(doc, credit_account, debit_account, against,
+			amount, base_amount, end_date, project, account_currency, item.cost_center, item.name)
+
+		if getdate(end_date) < getdate(posting_date) and not last_gl_entry:
+			_book_deferred_revenue_or_expense(item)
+
+
+	for item in doc.get('items'):
+		if item.get(enable_check):
+			_book_deferred_revenue_or_expense(item)
+
+def make_gl_entries(doc, credit_account, debit_account, against,
+	amount, base_amount, posting_date, project, account_currency, cost_center, voucher_detail_no):
+	# GL Entry for crediting the amount in the deferred expense
+	from erpnext.accounts.general_ledger import make_gl_entries
+
+	gl_entries = []
+	gl_entries.append(
+		doc.get_gl_dict({
+			"account": credit_account,
+			"against": against,
+			"credit": base_amount,
+			"credit_in_account_currency": amount,
+			"cost_center": cost_center,
+			"voucher_detail_no": voucher_detail_no,
+			'posting_date': posting_date,
+			'project': project
+		}, account_currency)
+	)
+	# GL Entry to debit the amount from the expense
+	gl_entries.append(
+		doc.get_gl_dict({
+			"account": debit_account,
+			"against": against,
+			"debit": base_amount,
+			"debit_in_account_currency": amount,
+			"cost_center": cost_center,
+			"voucher_detail_no": voucher_detail_no,
+			'posting_date': posting_date,
+			'project': project
+		}, account_currency)
+	)
+
 	if gl_entries:
 		try:
 			make_gl_entries(gl_entries, cancel=(doc.docstatus == 2), merge_entries=True)
 			frappe.db.commit()
 		except:
 			frappe.db.rollback()
-			frappe.log_error(message = frappe.get_traceback(), title = _("Error while processing deferred accounting for {0}").format(doc.name))
\ No newline at end of file
+			title = _("Error while processing deferred accounting for {0}").format(doc.name)
+			traceback = frappe.get_traceback()
+			frappe.log_error(message=traceback , title=title)
+			sendmail_to_system_managers(title, traceback)
\ No newline at end of file
diff --git a/erpnext/accounts/doctype/account/test_account.py b/erpnext/accounts/doctype/account/test_account.py
index 4c057d9..90177c6 100644
--- a/erpnext/accounts/doctype/account/test_account.py
+++ b/erpnext/accounts/doctype/account/test_account.py
@@ -144,7 +144,7 @@
 
 		# related to Account Inventory Integration
 		["_Test Account Stock In Hand", "Current Assets", 0, None, None],
-		
+
 		# fixed asset depreciation
 		["_Test Fixed Asset", "Current Assets", 0, "Fixed Asset", None],
 		["_Test Accumulated Depreciations", "Current Assets", 0, None, None],
@@ -181,13 +181,17 @@
 	return account
 
 def create_account(**kwargs):
-	account = frappe.get_doc(dict(
-		doctype = "Account",
-		account_name = kwargs.get('account_name'),
-		account_type = kwargs.get('account_type'),
-		parent_account = kwargs.get('parent_account'),
-		company = kwargs.get('company')
-	))
-	
-	account.save()
-	return account.name
+	account = frappe.db.get_value("Account", filters={"account_name": kwargs.get("account_name"), "company": kwargs.get("company")})
+	if account:
+		return account
+	else:
+		account = frappe.get_doc(dict(
+			doctype = "Account",
+			account_name = kwargs.get('account_name'),
+			account_type = kwargs.get('account_type'),
+			parent_account = kwargs.get('parent_account'),
+			company = kwargs.get('company')
+		))
+
+		account.save()
+		return account.name
diff --git a/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
index f9364e2..45a2950 100644
--- a/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
@@ -14,8 +14,9 @@
 from erpnext.exceptions import InvalidAccountCurrency, InvalidCurrency
 from erpnext.stock.doctype.serial_no.serial_no import SerialNoWarehouseError
 from frappe.model.naming import make_autoname
-from erpnext.accounts.doctype.account.test_account import get_inventory_account
+from erpnext.accounts.doctype.account.test_account import get_inventory_account, create_account
 from erpnext.controllers.taxes_and_totals import get_itemised_tax_breakup_data
+from erpnext.stock.doctype.item.test_item import create_item
 from six import iteritems
 class TestSalesInvoice(unittest.TestCase):
 	def make(self):
@@ -762,7 +763,7 @@
 		set_perpetual_inventory(0)
 
 		frappe.db.sql("delete from `tabPOS Profile`")
-	
+
 	def test_pos_si_without_payment(self):
 		set_perpetual_inventory()
 		make_pos_profile()
@@ -1514,6 +1515,56 @@
 		accounts_settings.allow_cost_center_in_entry_of_bs_account = 0
 		accounts_settings.save()
 
+	def test_deferred_revenue(self):
+		deferred_account = create_account(account_name="Deferred Revenue",
+			parent_account="Current Liabilities - _TC", company="_Test Company")
+
+		item = create_item("_Test Item for Deferred Accounting")
+		item.enable_deferred_revenue = 1
+		item.deferred_revenue_account = deferred_account
+		item.no_of_months = 12
+		item.save()
+
+		si = create_sales_invoice(item=item.name, posting_date="2019-01-10", do_not_submit=True)
+		si.items[0].enable_deferred_revenue = 1
+		si.items[0].service_start_date = "2019-01-10"
+		si.items[0].service_end_date = "2019-03-15"
+		si.items[0].deferred_revenue_account = deferred_account
+		si.save()
+		si.submit()
+
+		from erpnext.accounts.deferred_revenue import convert_deferred_revenue_to_income
+		convert_deferred_revenue_to_income(start_date="2019-01-01", end_date="2019-01-31")
+
+		expected_gle = [
+			[deferred_account, 33.85, 0.0, "2019-01-31"],
+			["Sales - _TC", 0.0, 33.85, "2019-01-31"]
+		]
+
+		self.check_gl_entries(si.name, expected_gle, "2019-01-10")
+
+		convert_deferred_revenue_to_income(start_date="2019-01-01", end_date="2019-03-31")
+
+		expected_gle = [
+			[deferred_account, 43.08, 0.0, "2019-02-28"],
+			["Sales - _TC", 0.0, 43.08, "2019-02-28"],
+			[deferred_account, 23.07, 0.0, "2019-03-15"],
+			["Sales - _TC", 0.0, 23.07, "2019-03-15"]
+		]
+
+		self.check_gl_entries(si.name, expected_gle, "2019-01-31")
+
+	def check_gl_entries(self, voucher_no, expected_gle, posting_date):
+		gl_entries = frappe.db.sql("""select account, debit, credit, posting_date
+			from `tabGL Entry`
+			where voucher_type='Sales Invoice' and voucher_no=%s and posting_date > %s
+			order by posting_date asc, account asc""", (voucher_no, posting_date), as_dict=1)
+
+		for i, gle in enumerate(gl_entries):
+			self.assertEqual(expected_gle[i][0], gle.account)
+			self.assertEqual(expected_gle[i][1], gle.debit)
+			self.assertEqual(expected_gle[i][2], gle.credit)
+			self.assertEqual(getdate(expected_gle[i][3]), gle.posting_date)
 
 def create_sales_invoice(**args):
 	si = frappe.new_doc("Sales Invoice")
@@ -1611,4 +1662,4 @@
 	if against_voucher_type == 'Purchase Invoice':
 		bal = bal * -1
 
-	return bal
+	return bal
\ No newline at end of file
diff --git a/erpnext/stock/doctype/item/test_item.py b/erpnext/stock/doctype/item/test_item.py
index d02559e..aa67c33 100644
--- a/erpnext/stock/doctype/item/test_item.py
+++ b/erpnext/stock/doctype/item/test_item.py
@@ -393,3 +393,6 @@
 			"company": "_Test Company"
 		})
 		item.save()
+	else:
+		item = frappe.get_doc("Item", item_code)
+	return item