diff --git a/app/models/budget.rb b/app/models/budget.rb
index 2347c96..0f82f96 100644
--- a/app/models/budget.rb
+++ b/app/models/budget.rb
@@ -50,6 +50,14 @@ class Budget
     return self.budget - self.spent
   end
   
+  def overruns
+    if self.left > 0
+      return 0
+    else
+      return self.left * -1
+    end
+  end
+  
   def progress
     return 100 unless self.deliverables.size > 0
     
@@ -62,7 +70,6 @@ class Budget
     return (balance / self.budget).round
   end
   
-  # TODO
   def score
     return self.progress - self.budget_ratio
   end
diff --git a/spec/models/budget_spec.rb b/spec/models/budget_spec.rb
index b8a685c..b872709 100644
--- a/spec/models/budget_spec.rb
+++ b/spec/models/budget_spec.rb
@@ -241,3 +241,25 @@ describe Budget, '.left' do
     @budget.left.should eql(1500.0)
   end
 end
+
+describe Budget, '.overruns' do
+  it 'should be 0 if there is still unspent budget' do
+    @project = mock_model(Project)
+    Project.stub!(:find).with(@project.id).and_return(@project)
+    
+    @budget = Budget.new(@project.id)  
+    @budget.should_receive(:left).and_return(1500.0)
+
+    @budget.overruns.should eql(0)
+  end
+
+  it 'should be calculated by the total budget and total spent of the deliverables' do
+    @project = mock_model(Project)
+    Project.stub!(:find).with(@project.id).and_return(@project)
+    
+    @budget = Budget.new(@project.id)  
+    @budget.should_receive(:left).twice.and_return(-1500.0)
+
+    @budget.overruns.should eql(1500.0)
+  end
+end