diff --git a/erpnext/hr/doctype/payroll_entry/payroll_entry.py b/erpnext/hr/doctype/payroll_entry/payroll_entry.py
index 9373d1a..10cbd13 100644
--- a/erpnext/hr/doctype/payroll_entry/payroll_entry.py
+++ b/erpnext/hr/doctype/payroll_entry/payroll_entry.py
@@ -40,7 +40,7 @@
 				{"company": self.company, "salary_slip_based_on_timesheet":self.salary_slip_based_on_timesheet})
 		if sal_struct:
 			cond += "and t2.salary_structure IN %(sal_struct)s "
-			cond += "and ((%(from_date)s between t2.from_date and ifnull(t2.to_date, '2199-12-31')) or (%(to_date)s between t2.from_date and ifnull(t2.to_date, '2199-12-31')) or (t2.from_date between %(from_date)s and %(to_date)s))"
+			cond += "and %(from_date)s >= t2.from_date"
 			emp_list = frappe.db.sql("""
 				select
 					t1.name as employee, t1.employee_name, t1.department, t1.designation, t2.name
@@ -49,7 +49,7 @@
 				where
 					t1.name = t2.employee
 					and t2.docstatus = 1
-			%s """% cond, {"sal_struct": sal_struct, "from_date": self.start_date, "to_date": self.end_date}, as_dict=True)
+			%s order by t2.from_date desc limit 1"""% cond, {"sal_struct": sal_struct, "from_date": self.start_date}, as_dict=True)
 			return emp_list
 
 	def fill_employee_details(self):
diff --git a/erpnext/hr/doctype/salary_slip/salary_slip.py b/erpnext/hr/doctype/salary_slip/salary_slip.py
index 42b63b6..944ba7c 100644
--- a/erpnext/hr/doctype/salary_slip/salary_slip.py
+++ b/erpnext/hr/doctype/salary_slip/salary_slip.py
@@ -230,12 +230,11 @@
 			cond = """and payroll_frequency = '%(payroll_frequency)s'""" % {"payroll_frequency": self.payroll_frequency}
 
 		st_name = frappe.db.sql("""select salary_structure from `tabSalary Structure Assignment`
-			where employee=%s and (from_date <= %s or from_date <= %s)
-			and (to_date is null or to_date >= %s or to_date >= %s)
+			where employee=%s and (from_date <= %s or from_date <= %s or from_date <= %s)
 			and docstatus = 1
 			and salary_structure in (select name from `tabSalary Structure`
-				where is_active = 'Yes'%s)
-			"""% ('%s', '%s', '%s','%s','%s', cond),(self.employee, self.start_date, joining_date, self.end_date, relieving_date))
+				where is_active = 'Yes' %s) order by from_date desc limit 1
+			""", (self.employee, self.start_date, self.end_date, joining_date, cond))
 
 		if st_name:
 			if len(st_name) > 1:
diff --git a/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.json b/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.json
index 221550f..95308dc 100644
--- a/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.json
+++ b/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.json
@@ -213,38 +213,6 @@
   {
    "allow_bulk_edit": 0, 
    "allow_in_quick_entry": 0, 
-   "allow_on_submit": 1, 
-   "bold": 0, 
-   "collapsible": 0, 
-   "columns": 0, 
-   "fieldname": "to_date", 
-   "fieldtype": "Date", 
-   "hidden": 0, 
-   "ignore_user_permissions": 0, 
-   "ignore_xss_filter": 0, 
-   "in_filter": 0, 
-   "in_global_search": 0, 
-   "in_list_view": 0, 
-   "in_standard_filter": 0, 
-   "label": "To Date", 
-   "length": 0, 
-   "no_copy": 0, 
-   "permlevel": 0, 
-   "precision": "", 
-   "print_hide": 0, 
-   "print_hide_if_no_value": 0, 
-   "read_only": 0, 
-   "remember_last_selected_value": 0, 
-   "report_hide": 0, 
-   "reqd": 0, 
-   "search_index": 0, 
-   "set_only_once": 0, 
-   "translatable": 0, 
-   "unique": 0
-  }, 
-  {
-   "allow_bulk_edit": 0, 
-   "allow_in_quick_entry": 0, 
    "allow_on_submit": 0, 
    "bold": 0, 
    "collapsible": 0, 
@@ -444,7 +412,7 @@
  "issingle": 0, 
  "istable": 0, 
  "max_attachments": 0, 
- "modified": "2018-06-13 16:18:19.784377", 
+ "modified": "2018-06-22 14:54:05.494234", 
  "modified_by": "Administrator", 
  "module": "HR", 
  "name": "Salary Structure Assignment", 
diff --git a/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.py b/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.py
index 2168a36..210f75d 100644
--- a/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.py
+++ b/erpnext/hr/doctype/salary_structure_assignment/salary_structure_assignment.py
@@ -13,13 +13,15 @@
 class SalaryStructureAssignment(Document):
 	def validate(self):
 		self.validate_dates()
-		self.validate_duplicate_assignments()
 
 	def validate_dates(self):
 		joining_date, relieving_date = frappe.db.get_value("Employee", self.employee,
 			["date_of_joining", "relieving_date"])
 
 		if self.from_date:
+			if frappe.db.exists("Salary Structure Assignment", {"employee": self.employee, "from_date": self.from_date, "docstatus": 1}):
+				frappe.throw("Salary Structure Assignment for Employee already exists")
+
 			if joining_date and getdate(self.from_date) < joining_date:
 				frappe.throw(_("From Date {0} cannot be before employee's joining Date {1}")
 					.format(self.from_date, joining_date))
@@ -29,51 +31,15 @@
 				frappe.throw(_("From Date {0} cannot be after employee's relieving Date {1}")
 					.format(self.from_date, relieving_date))
 
-		if self.to_date:
-			if self.from_date and getdate(self.from_date) > getdate(self.to_date):
-				frappe.throw(_("From Date {0} cannot be after To Date {1}")
-					.format(self.from_date, self.to_date))
-			if relieving_date and getdate(self.to_date) > getdate(relieving_date) and not self.flags.old_employee:
-				frappe.throw(_("To Date {0} cannot be after employee's relieving Date {1}")
-					.format(self.to_date, relieving_date))
-
-	def validate_duplicate_assignments(self):
-		if not self.name:
- 			# hack! if name is null, it could cause problems with !=
- 			self.name = "New "+self.doctype
-		assignment = frappe.db.sql("""
-			select name from `tabSalary Structure Assignment`
-			where employee=%(employee)s
-			and name != %(name)s
-			and docstatus != 2
-			and (
-				(%(from_date)s between from_date and ifnull(to_date, '2199-12-31'))
-				or (%(to_date)s between from_date and ifnull(to_date, '2199-12-31'))
-				or (from_date between %(from_date)s and %(to_date)s)
-			)""", {
-				'employee': self.employee,
-				'from_date': self.from_date,
-				'to_date': (self.to_date or '2199-12-31'),
-				'name': self.name
-			})
-
-		if assignment:
-			frappe.throw(_("Active Salary Structure Assignment {0} found for employee {1} for the given dates").
-				format(assignment[0][0], self.employee), DuplicateAssignment)
-
 def get_assigned_salary_structure(employee, on_date):
 	if not employee or not on_date:
 		return None
-
 	salary_structure = frappe.db.sql("""
 		select salary_structure from `tabSalary Structure Assignment`
 		where employee=%(employee)s
 		and docstatus = 1
-		and (
-			(%(on_date)s between from_date and ifnull(to_date, '2199-12-31'))
-		)""", {
+		and %(on_date)s > from_date order by from_date desc limit 1""", {
 			'employee': employee,
 			'on_date': on_date,
 		})
-
 	return salary_structure[0][0] if salary_structure else None
diff --git a/erpnext/hr/utils.py b/erpnext/hr/utils.py
index 7a861ac..6c31195 100644
--- a/erpnext/hr/utils.py
+++ b/erpnext/hr/utils.py
@@ -303,9 +303,7 @@
 		select * from `tabSalary Structure Assignment`
 		where employee=%(employee)s
 		and docstatus = 1
-		and (
-			(%(on_date)s between from_date and ifnull(to_date, '2199-12-31'))
-		)""", {
+		and %(on_date)s >= from_date order by from_date desc limit 1""", {
 			'employee': employee,
 			'on_date': date,
 		}, as_dict=1)