diff --git a/src/oops/SOLID/openClosePrinciple/after/client/CalculateTaxesClient.java b/src/oops/SOLID/openClosePrinciple/after/client/CalculateTaxesClient.java
new file mode 100644
index 00000000..c6767696
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/client/CalculateTaxesClient.java
@@ -0,0 +1,35 @@
+package oops.SOLID.openClosePrinciple.after.client;
+
+import oops.SOLID.openClosePrinciple.after.employees.Employee;
+import oops.SOLID.openClosePrinciple.after.persistence.EmployeeRepository;
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculator;
+
+import java.text.NumberFormat;
+import java.util.List;
+import java.util.Locale;
+
+
+public class CalculateTaxesClient {
+    public static void main(String[] args) {
+       
+        EmployeeRepository repository = new EmployeeRepository();
+
+        // Grab employees
+        List<Employee> employees = repository.findAll();
+
+        // Calculate taxes
+        Locale locale = new Locale("en", "US");
+        NumberFormat currencyFormatter = NumberFormat.getCurrencyInstance(locale);
+   
+
+        double totalTaxes = 0;
+        for (Employee employee: employees){
+
+            // compute individual tax
+            double tax = employee.TaxCalculate();
+            String formattedTax = currencyFormatter.format(tax);
+            // add to company total taxes
+            totalTaxes += tax;
+        }
+    }
+}
diff --git a/src/oops/SOLID/openClosePrinciple/after/employees/Employee.java b/src/oops/SOLID/openClosePrinciple/after/employees/Employee.java
new file mode 100644
index 00000000..d32cfaf5
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/employees/Employee.java
@@ -0,0 +1,63 @@
+package oops.SOLID.openClosePrinciple.after.employees;
+
+/*
+Models an employee form a business perspective
+ */
+public abstract class Employee {
+    private String firstName;
+    private String lastName;
+    private int monthlyIncome;
+    private int nbHoursPerWeek;
+
+    public Employee(String fullName, int monthlyIncome){
+        setMonthlyIncome(monthlyIncome);
+
+        String[] names = fullName.split(" ");
+        this.firstName = names[0];
+        this.lastName = names[1];
+    }
+
+    public String getEmail() {
+        return this.firstName + "." +
+                this.lastName +
+                "@globomanticshr.com";
+    }
+
+    @Override
+    public String toString() {
+        return this.firstName + " " +
+                this.lastName + " - " +
+                this.monthlyIncome;
+    }
+
+    public int getMonthlyIncome() {
+        return monthlyIncome;
+    }
+
+    public void setMonthlyIncome(int monthlyIncome) {
+        if(monthlyIncome < 0){
+            throw new IllegalArgumentException("Income must be positive");
+        }
+
+        this.monthlyIncome = monthlyIncome;
+    }
+
+    public int getNbHoursPerWeek() {
+        return nbHoursPerWeek;
+    }
+
+    public void setNbHoursPerWeek(int nbHoursPerWeek) {
+        if(nbHoursPerWeek <= 0){
+            throw new IllegalArgumentException("Income must be positive");
+        }
+
+        this.nbHoursPerWeek = nbHoursPerWeek;
+    }
+
+    public String getFullName(){
+        return this.firstName + " " + this.lastName;
+    }
+
+    public abstract double TaxCalculate();
+}
+
diff --git a/src/oops/SOLID/openClosePrinciple/after/employees/FullTimeEmployee.java b/src/oops/SOLID/openClosePrinciple/after/employees/FullTimeEmployee.java
new file mode 100644
index 00000000..9a2cd547
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/employees/FullTimeEmployee.java
@@ -0,0 +1,16 @@
+package oops.SOLID.openClosePrinciple.after.employees;
+
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculator;
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculatorFullTimeEmp;
+
+public class FullTimeEmployee extends Employee {
+    public FullTimeEmployee(String fullName, int monthlyIncome) {
+        super(fullName, monthlyIncome);
+        this.setNbHoursPerWeek(40);
+    }
+
+    public double TaxCalculate(){
+        TaxCalculator calculator = new TaxCalculatorFullTimeEmp();
+        return calculator.calculate(this);
+    }
+}
diff --git a/src/oops/SOLID/openClosePrinciple/after/employees/Intern.java b/src/oops/SOLID/openClosePrinciple/after/employees/Intern.java
new file mode 100644
index 00000000..06e25bf0
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/employees/Intern.java
@@ -0,0 +1,16 @@
+package oops.SOLID.openClosePrinciple.after.employees;
+
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculator;
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculatorIntern;
+
+public class Intern extends Employee {
+    public Intern(String fullName, int monthlyIncome, int nbHours) {
+        super(fullName, monthlyIncome);
+        setNbHoursPerWeek(nbHours);
+    }
+
+    public double TaxCalculate(){
+        TaxCalculator calculator = new TaxCalculatorIntern();
+        return calculator.calculate(this);
+    }
+}
diff --git a/src/oops/SOLID/openClosePrinciple/after/employees/PartTimeEmployee.java b/src/oops/SOLID/openClosePrinciple/after/employees/PartTimeEmployee.java
new file mode 100644
index 00000000..b0cc3077
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/employees/PartTimeEmployee.java
@@ -0,0 +1,17 @@
+package oops.SOLID.openClosePrinciple.after.employees;
+
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculator;
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculatorIntern;
+import oops.SOLID.openClosePrinciple.after.taxes.TaxCalculatorPartTimeEmp;
+
+public class PartTimeEmployee extends Employee {
+    public PartTimeEmployee(String fullName, int monthlyIncome) {
+        super(fullName, monthlyIncome);
+        this.setNbHoursPerWeek(20);
+    }
+
+    public double TaxCalculate(){
+        TaxCalculator calculator = new TaxCalculatorPartTimeEmp();
+        return calculator.calculate(this);
+    }
+}
\ No newline at end of file
diff --git a/src/oops/SOLID/openClosePrinciple/after/persistence/EmployeeRepository.java b/src/oops/SOLID/openClosePrinciple/after/persistence/EmployeeRepository.java
new file mode 100644
index 00000000..ed700484
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/persistence/EmployeeRepository.java
@@ -0,0 +1,23 @@
+package oops.SOLID.openClosePrinciple.after.persistence;
+
+import oops.SOLID.openClosePrinciple.after.employees.Employee;
+import oops.SOLID.openClosePrinciple.after.employees.FullTimeEmployee;
+import oops.SOLID.openClosePrinciple.after.employees.PartTimeEmployee;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class EmployeeRepository {
+
+    public List<Employee> findAll(){
+
+        // Employees are kept in memory for simplicity
+        Employee anna = new FullTimeEmployee("Anna Smith", 2000);
+        Employee billy = new FullTimeEmployee("Billy Leech", 920);
+
+        Employee steve = new PartTimeEmployee("Steve Jones", 800);
+        Employee magda = new PartTimeEmployee("Magda Iovan", 920);
+
+        return Arrays.asList(anna, billy, steve, magda);
+    }
+}
\ No newline at end of file
diff --git a/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculator.java b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculator.java
new file mode 100644
index 00000000..f88d6691
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculator.java
@@ -0,0 +1,7 @@
+package oops.SOLID.openClosePrinciple.after.taxes;
+
+import oops.SOLID.openClosePrinciple.after.employees.Employee;
+
+public interface TaxCalculator {
+    double calculate(Employee employee);
+}
\ No newline at end of file
diff --git a/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorFullTimeEmp.java b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorFullTimeEmp.java
new file mode 100644
index 00000000..1fa1f657
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorFullTimeEmp.java
@@ -0,0 +1,18 @@
+package oops.SOLID.openClosePrinciple.after.taxes;
+
+import oops.SOLID.openClosePrinciple.after.employees.Employee;
+
+public class TaxCalculatorFullTimeEmp implements TaxCalculator{
+
+    private final static int INCOME_TAX_PERCENTAGE = 30;
+    private final static int PROFESSIONAL_TAX_PERCENTAGE = 2;
+    private final static int EDUCATION_CESS_PERCENTAGE = 1;
+
+    @Override
+    public double calculate(Employee employee) {
+        return
+                (employee.getMonthlyIncome()* 12 * PROFESSIONAL_TAX_PERCENTAGE) / 100 +
+                        (employee.getMonthlyIncome()* 12 * INCOME_TAX_PERCENTAGE) / 100 +
+                        (employee.getMonthlyIncome()* 12 * EDUCATION_CESS_PERCENTAGE)/100;
+    }
+}
diff --git a/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorIntern.java b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorIntern.java
new file mode 100644
index 00000000..577fa7b9
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorIntern.java
@@ -0,0 +1,16 @@
+package oops.SOLID.openClosePrinciple.after.taxes;
+
+import oops.SOLID.openClosePrinciple.after.employees.Employee;
+
+public class TaxCalculatorIntern implements TaxCalculator{
+    private final static int TAX_FREE = 300000;
+    private final static int TAX_PERCENTAGE = 15;
+
+    @Override
+    public double calculate(Employee employee) {
+        if(employee.getMonthlyIncome() * 12 <= TAX_FREE)
+            return 0D;
+
+        return (employee.getMonthlyIncome()*12*TAX_PERCENTAGE)/100;
+    }
+}
diff --git a/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorPartTimeEmp.java b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorPartTimeEmp.java
new file mode 100644
index 00000000..e2714f4a
--- /dev/null
+++ b/src/oops/SOLID/openClosePrinciple/after/taxes/TaxCalculatorPartTimeEmp.java
@@ -0,0 +1,17 @@
+package oops.SOLID.openClosePrinciple.after.taxes;
+
+import oops.SOLID.openClosePrinciple.after.employees.Employee;
+
+public class TaxCalculatorPartTimeEmp implements TaxCalculator{
+    private final static int INCOME_TAX_PERCENTAGE = 20;
+    private final static int PROFESSIONAL_TAX_PERCENTAGE = 3;
+    private final static int EDUCATION_CESS_PERCENTAGE = 1;
+
+    @Override
+    public double calculate(Employee employee) {
+        return
+                (employee.getMonthlyIncome()* 12 * PROFESSIONAL_TAX_PERCENTAGE) / 100 +
+                        (employee.getMonthlyIncome()* 12 * INCOME_TAX_PERCENTAGE) / 100 +
+                        (employee.getMonthlyIncome()* 12 * EDUCATION_CESS_PERCENTAGE)/100;
+    }
+}