diff --git a/registrasion/controllers/invoice.py b/registrasion/controllers/invoice.py
index c5a527ca..de401d31 100644
--- a/registrasion/controllers/invoice.py
+++ b/registrasion/controllers/invoice.py
@@ -126,6 +126,23 @@ class InvoiceController(object):
 
         return invoice
 
+    def can_view(self, user=None, access_code=None):
+        ''' Returns true if the accessing user is allowed to view this invoice,
+        or if the given access code matches this invoice's user's access code.
+        '''
+
+        if user == self.invoice.user:
+            return True
+
+        if user.is_staff:
+            return True
+
+        if self.invoice.user.attendee.access_code == access_code:
+            return True
+
+        return False
+
+
     def _refresh(self):
         ''' Refreshes the underlying invoice and cart objects. '''
         self.invoice.refresh_from_db()
diff --git a/registrasion/urls.py b/registrasion/urls.py
index eb0606df..0949e4b4 100644
--- a/registrasion/urls.py
+++ b/registrasion/urls.py
@@ -7,8 +7,11 @@ urlpatterns = patterns(
     url(r"^category/([0-9]+)$", "product_category", name="product_category"),
     url(r"^checkout$", "checkout", name="checkout"),
     url(r"^invoice/([0-9]+)$", "invoice", name="invoice"),
+    url(r"^invoice/([0-9]+)/([A-Z0-9]+)$", views.invoice, name="invoice"),
     url(r"^invoice/([0-9]+)/manual_payment$",
         views.manual_payment, name="manual_payment"),
+    url(r"^invoice_access/([A-Z0-9]+)$", views.invoice_access,
+        name="invoice_access"),
     url(r"^profile$", "edit_profile", name="attendee_edit"),
     url(r"^register$", "guided_registration", name="guided_registration"),
     url(r"^register/([0-9]+)$", "guided_registration",
diff --git a/registrasion/views.py b/registrasion/views.py
index da8687cc..251f0fba 100644
--- a/registrasion/views.py
+++ b/registrasion/views.py
@@ -424,18 +424,41 @@ def checkout_errors(request, errors):
     return render(request, "registrasion/checkout_errors.html", data)
 
 
-@login_required
-def invoice(request, invoice_id):
-    ''' Displays an invoice for a given invoice id. '''
+def invoice_access(request, access_code):
+    ''' Redirects to the first unpaid invoice for the attendee that matches
+    the given access code, if any. '''
+
+    invoices = rego.Invoice.objects.filter(
+        user__attendee__access_code=access_code,
+        status=rego.Invoice.STATUS_UNPAID,
+    ).order_by("issue_time")
+
+    if not invoices:
+        raise Http404()
+
+    invoice = invoices[0]
+
+    return redirect("invoice", invoice.id, access_code)
+
+
+def invoice(request, invoice_id, access_code=None):
+    ''' Displays an invoice for a given invoice id.
+    This view is not authenticated, but it will only allow access to either:
+    the user the invoice belongs to; staff; or a request made with the correct
+    access code.
+    '''
 
     invoice_id = int(invoice_id)
     inv = rego.Invoice.objects.get(pk=invoice_id)
 
-    if request.user != inv.cart.user and not request.user.is_staff:
-        raise Http404()
-
     current_invoice = InvoiceController(inv)
 
+    if not current_invoice.can_view(
+            user=request.user,
+            access_code=access_code,
+        ):
+        raise Http404()
+
     data = {
         "invoice": current_invoice.invoice,
     }