diff --git a/erpnext/hr/doctype/process_payroll/process_payroll.js b/erpnext/hr/doctype/process_payroll/process_payroll.js
index 0ad8cec..cfb646d 100644
--- a/erpnext/hr/doctype/process_payroll/process_payroll.js
+++ b/erpnext/hr/doctype/process_payroll/process_payroll.js
@@ -7,6 +7,7 @@
 		frm.doc.start_date = '';
 		frm.doc.end_date = '';
 		frm.doc.payroll_frequency = '';
+		frm.toggle_reqd(['payroll_frequency'], !frm.doc.salary_slip_based_on_timesheet);
 	},
 
 	refresh: function(frm) {
@@ -25,6 +26,10 @@
 		frm.trigger("set_start_end_dates");
 	},
 
+	salary_slip_based_on_timesheet: function(frm) {
+		frm.toggle_reqd(['payroll_frequency'], !frm.doc.salary_slip_based_on_timesheet);
+	},
+
 	payment_account: function(frm) {
 		frm.toggle_display(['make_bank_entry'], (frm.doc.payment_account!="" && frm.doc.payment_account!="undefined"));
 	},
diff --git a/erpnext/hr/doctype/process_payroll/process_payroll.py b/erpnext/hr/doctype/process_payroll/process_payroll.py
index 45030cb..7741263 100644
--- a/erpnext/hr/doctype/process_payroll/process_payroll.py
+++ b/erpnext/hr/doctype/process_payroll/process_payroll.py
@@ -68,7 +68,7 @@
 
 
 	def check_mandatory(self):
-		for fieldname in ['company', 'payroll_frequency', 'start_date', 'end_date']:
+		for fieldname in ['company', 'start_date', 'end_date']:
 			if not self.get(fieldname):
 				frappe.throw(_("Please set {0}").format(self.meta.get_label(fieldname)))