diff --git a/app/models/job.rb b/app/models/job.rb
index 55d3a29..8157c1d 100644
--- a/app/models/job.rb
+++ b/app/models/job.rb
@@ -15,8 +15,9 @@ class Job < ActiveRecord::Base
   scope :project_or_parent, ->(project) { where(project_id: [project.id, project.parent&.id]) }
 
   def with_all_time_budgets
+    time_budgets.build(job_id: id, activity_id: nil) unless time_budgets.where(activity_id: nil).exists?
     TimeEntryActivity.where.not(id: time_budgets.pluck(:activity_id)).each do |activity|
-      time_budgets << TimeBudget.new(job_id: id, activity_id: activity.id)
+      time_budgets.build(job_id: id, activity_id: activity.id)
     end
     self
   end
@@ -42,7 +43,7 @@ class Job < ActiveRecord::Base
   end
 
   def total_time_logged_for(activity)
-    TimeEntry.where(job_id: id, activity_id: activity.id)
+    TimeEntry.where(job_id: id, activity_id: activity&.id)
              .sum(:hours)
   end
 
diff --git a/app/models/time_budget.rb b/app/models/time_budget.rb
index 83198b4..ef1af59 100644
--- a/app/models/time_budget.rb
+++ b/app/models/time_budget.rb
@@ -3,9 +3,11 @@ class TimeBudget < ActiveRecord::Base
             presence: true
 
   validates :activity_id,
-            inclusion: { in: TimeEntryActivity.pluck(:id) }
+            inclusion: { in: TimeEntryActivity.pluck(:id) },
+            allow_nil: true
+
+  validates_uniqueness_of :job_id, scope: :activity_id, message: "Only one time budget can exist for each activity type"
 
   belongs_to :job
   belongs_to :activity, class_name: "TimeEntryActivity"
-
 end
diff --git a/app/views/jobs/_budget.html.erb b/app/views/jobs/_budget.html.erb
index 1f54c16..284e127 100644
--- a/app/views/jobs/_budget.html.erb
+++ b/app/views/jobs/_budget.html.erb
@@ -1,4 +1,4 @@
-<div class="label"><%= budget.activity.name %></div>
+<div class="label"><%= budget.activity&.name || "Unassigned" %></div>
 <div class="value">
   <%= l_hours_short(
     budget.job.total_time_logged_for(budget.activity)
diff --git a/app/views/jobs/_form.html.erb b/app/views/jobs/_form.html.erb
index 8770a86..026d0f7 100644
--- a/app/views/jobs/_form.html.erb
+++ b/app/views/jobs/_form.html.erb
@@ -1,4 +1,5 @@
-<%= form_with model: @job, id: "job_form" do |f| %>
+<%= form_with model: @job, url: job_path(@job, project_id: @job.project.id), id: "job_form" do |f| %>
+  <%= error_messages_for @job %>
   <div class="box tabular">
     <p>
     <%= f.label :name %>
@@ -16,7 +17,7 @@
     <%= f.label :ends_on %>
     <%= f.date_field :ends_on %>
 
-    <%= f.hidden_field :project_id, value: @project.id %>
+    <%= f.hidden_field :project_id, value: @job.project.id %>
 
     <p>
     <%= f.label :external_project_id %>
@@ -26,7 +27,7 @@
       <legend>Budget</legend>
       <%= f.fields_for :time_budgets do |ff| %>
         <p>
-        <%= ff.label :hours, ff.object.activity.name %>
+        <%= ff.label :hours, ff.object.activity&.name || "Unassigned" %>
         <%= ff.number_field :hours %>
         <%= ff.hidden_field :activity_id %>
         <%= ff.hidden_field :job_id %>