diff --git a/app/models/rate.rb b/app/models/rate.rb
index bbe0347..71256d2 100644
--- a/app/models/rate.rb
+++ b/app/models/rate.rb
@@ -6,6 +6,8 @@ class Rate < ActiveRecord::Base
   validates_presence_of :user_id
   validates_presence_of :date_in_effect
   
+  before_save :unlocked?
+  
   named_scope :history_for_user, lambda { |user|
     {
       :conditions => { :user_id => user.id },
@@ -16,4 +18,8 @@ class Rate < ActiveRecord::Base
   def locked?
     return self.time_entries.length > 0
   end
+  
+  def unlocked?
+    return !self.locked?
+  end
 end
diff --git a/spec/models/rate_spec.rb b/spec/models/rate_spec.rb
index 6601601..4698d94 100644
--- a/spec/models/rate_spec.rb
+++ b/spec/models/rate_spec.rb
@@ -70,3 +70,33 @@ describe Rate, 'locked?' do
   end
   
 end
+
+describe Rate, 'locked?' do
+  it 'should be false if a Time Entry is associated' do
+    rate = Rate.new
+    rate.time_entries << mock_model(TimeEntry)
+    rate.unlocked?.should be_false
+  end
+  
+  it 'should be true if no Time Entries are associated' do
+    rate = Rate.new
+    rate.unlocked?.should be_true
+  end
+  
+end
+
+describe Rate, 'save' do
+  include RateSpecHelper
+
+  it 'should save normally if a Rate is not locked' do
+    rate = Rate.new(rate_valid_attributes)
+    rate.stub!(:locked?).and_return(false)
+    rate.save.should eql(true)
+  end
+
+  it 'should not save if a Rate is locked' do
+    rate = Rate.new(rate_valid_attributes)
+    rate.stub!(:locked?).and_return(true)
+    rate.save.should eql(false)
+  end
+end