diff --git a/oops/polymorphism.go b/oops/polymorphism.go
new file mode 100644
index 00000000..62b09d03
--- /dev/null
+++ b/oops/polymorphism.go
@@ -0,0 +1,44 @@
+//polymorphism
+package main 
+import "fmt"
+type income interface {
+	calculate() int
+    source() string
+}
+type fixedbilling struct {
+	projectname string
+	biddedamount int
+}
+type timeandmaterial struct {
+	projectname string
+	noofhours int
+	hourlyrate int
+ }
+ func (fb fixedbilling) calculate() int {
+	 return fb.biddedamount
+ }
+ func (fb fixedbilling) source() string {
+	 return fb.projectname
+ }	 
+ func (tm timeandmaterial) calculate() int {
+	 return tm.noofhours * tm.hourlyrate
+ }
+ func (tm timeandmaterial) source() string {
+	return tm.projectname
+ }
+ func calculatenetincome(ic [] income) {
+	 var netincome int = 0
+	 for _,income := range ic {
+		 fmt.Printf("%s = %d" , income.source() , income.calculate())
+		 netincome = income.calculate()
+	 }
+	 fmt.Printf("\n netincome of organization = %d",netincome)
+ }
+ func main() {
+	 project1 := fixedbilling{projectname:"project1",biddedamount:8000}
+	 project2 :=fixedbilling{projectname:"project2",biddedamount:5000}
+	 project3 := timeandmaterial{projectname:"project3",noofhours:9,hourlyrate:1000}
+	 totalgenerated := [] income{project1,project2,project3}
+	 calculatenetincome(totalgenerated)
+	 
+ }