diff --git a/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.json b/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.json
index 9e53a97..32203d8 100644
--- a/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.json
+++ b/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.json
@@ -216,6 +216,38 @@
    "bold": 0, 
    "collapsible": 0, 
    "columns": 0, 
+   "fieldname": "total_amount", 
+   "fieldtype": "Currency", 
+   "hidden": 0, 
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+   "in_filter": 0, 
+   "in_global_search": 0, 
+   "in_list_view": 0, 
+   "in_standard_filter": 0, 
+   "label": "Total Exemption Amount", 
+   "length": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
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+  {
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    "fieldname": "section_break_5", 
    "fieldtype": "Section Break", 
    "hidden": 0, 
@@ -375,37 +407,6 @@
    "bold": 0, 
    "collapsible": 0, 
    "columns": 0, 
-   "fieldname": "column_break_12", 
-   "fieldtype": "Column Break", 
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-   "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, 
-   "columns": 0, 
    "fieldname": "rented_from_date", 
    "fieldtype": "Date", 
    "hidden": 0, 
@@ -470,6 +471,133 @@
    "bold": 0, 
    "collapsible": 0, 
    "columns": 0, 
+   "fieldname": "column_break_12", 
+   "fieldtype": "Column Break", 
+   "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, 
+   "length": 0, 
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+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
+   "read_only": 0, 
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+   "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, 
+   "columns": 0, 
+   "fieldname": "monthly_house_rent", 
+   "fieldtype": "Currency", 
+   "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": "Monthly House Rent", 
+   "length": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
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+  }, 
+  {
+   "allow_bulk_edit": 0, 
+   "allow_in_quick_entry": 0, 
+   "allow_on_submit": 0, 
+   "bold": 0, 
+   "collapsible": 0, 
+   "columns": 0, 
+   "fieldname": "monthly_hra_exemption", 
+   "fieldtype": "Currency", 
+   "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": "Monthly Eligible Amount", 
+   "length": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
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+  }, 
+  {
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+   "allow_in_quick_entry": 0, 
+   "allow_on_submit": 0, 
+   "bold": 0, 
+   "collapsible": 0, 
+   "columns": 0, 
+   "fieldname": "total_eligible_hra_exemption", 
+   "fieldtype": "Currency", 
+   "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": "Total Eligible HRA Exemption", 
+   "length": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
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    "fieldname": "attachment_section", 
    "fieldtype": "Section Break", 
    "hidden": 0, 
@@ -570,7 +698,7 @@
  "issingle": 0, 
  "istable": 0, 
  "max_attachments": 0, 
- "modified": "2018-05-29 13:54:55.004847", 
+ "modified": "2018-05-30 20:26:05.714414", 
  "modified_by": "Administrator", 
  "module": "HR", 
  "name": "Employee Tax Exemption Proof Submission", 
diff --git a/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.py b/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.py
index a0c003c..2be09ae 100644
--- a/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.py
+++ b/erpnext/hr/doctype/employee_tax_exemption_proof_submission/employee_tax_exemption_proof_submission.py
@@ -6,16 +6,52 @@
 import frappe
 from frappe.model.document import Document
 from frappe import _
-from erpnext.hr.utils import validate_tax_declaration
+from frappe.utils import date_diff, flt, getdate, get_first_day, get_last_day
+from erpnext.hr.utils import validate_tax_declaration, calculate_eligible_hra_exemption
 
 class EmployeeTaxExemptionProofSubmission(Document):
 	def validate(self):
 		validate_tax_declaration(self.tax_exemption_proofs)
-	#TODO: allow multiple?
-	# def before_submit(self):
-	# 	if frappe.db.exists({"doctype": "Employee Tax Exemption Proof Submission",
-	# 						"employee": self.employee,
-	# 						"payroll_period": self.payroll_period,
-	# 						"docstatus": 1}):
-	# 		frappe.throw(_("Proof Submission of {0} for period {1} already submitted.")\
-	# 		.format(self.employee, self.payroll_period), frappe.DocstatusTransitionError)
+		if self.house_rent_payment_amount:
+			self.validate_house_rent_dates()
+		self.get_monthly_hra()
+		self.calculate_hra_exemption()
+		self.calculate_total_exemption()
+
+	def get_monthly_hra(self):
+		factor = self.get_rented_days_factor()
+		self.monthly_house_rent = self.house_rent_payment_amount / factor
+
+	def validate_house_rent_dates(self):
+		if date_diff(self.rented_to_date, self.rented_from_date) < 14:
+			frappe.throw(_("House Rented dates should be atleast 15 days apart"))
+
+		proofs = frappe.db.sql("""select name from `tabEmployee Tax Exemption Proof Submission`
+			where docstatus=1 and employee='{0}' and payroll_period='{1}' and
+			(rented_from_date between '{2}' and '{3}' or rented_to_date between
+			'{2}' and '{2}')""".format(self.employee, self.payroll_period,
+			self.rented_from_date, self.rented_to_date))
+		if proofs:
+			frappe.throw(_("House rent paid days overlap with {0}").format(proofs[0][0]))
+
+	def calculate_hra_exemption(self):
+		exemptions = calculate_eligible_hra_exemption(self.company, self.employee, \
+						self.monthly_house_rent, self.rented_in_metro_city)
+		self.monthly_hra_exemption = exemptions["monthly_exemption"]
+		if self.monthly_hra_exemption:
+			factor = self.get_rented_days_factor(rounded=False)
+			self.total_eligible_hra_exemption = self.monthly_hra_exemption * factor
+		else:
+			self.monthly_hra_exemption, self.total_eligible_hra_exemption = 0, 0
+
+	def get_rented_days_factor(self, rounded=True):
+		factor = flt(date_diff(self.rented_to_date, self.rented_from_date) + 1)/30
+		factor = round(factor * 2)/2
+		return factor if factor else 0.5
+
+	def calculate_total_exemption(self):
+		self.total_amount = 0
+		for proof in self.tax_exemption_proofs:
+			self.total_amount += proof.amount
+		if self.monthly_house_rent and self.total_eligible_hra_exemption:
+			self.total_amount += self.total_eligible_hra_exemption