diff --git a/planetstack/core/models/__init__.py b/planetstack/core/models/__init__.py
index ac12370..b453a14 100644
--- a/planetstack/core/models/__init__.py
+++ b/planetstack/core/models/__init__.py
@@ -28,3 +28,4 @@
 from .reservation import ReservedResource
 from .reservation import Reservation
 from .network import Network, NetworkParameterType, NetworkParameter, NetworkSliver, NetworkTemplate, Router, NetworkSlice
+from .billing import Account, Invoice, Charge, UsableObject, Payment
diff --git a/planetstack/core/models/billing.py b/planetstack/core/models/billing.py
new file mode 100644
index 0000000..6d1c331
--- /dev/null
+++ b/planetstack/core/models/billing.py
@@ -0,0 +1,76 @@
+import datetime
+import os
+import socket
+from django.db import models
+from core.models import PlCoreBase, Site, Slice, Sliver, Deployment
+from django.contrib.contenttypes.models import ContentType
+from django.contrib.contenttypes import generic
+from django.db.models import Sum
+
+class Account(PlCoreBase):
+    site = models.ForeignKey(Site, related_name="accounts", help_text="Site for this account")
+
+    @property
+    def total_invoices(self):
+        # Since the amount of an invoice is the sum of it's charges, we can
+        # compute the sum of the invoices by summing all charges where
+        # charge.invoice != Null.
+        x=self.charges.filter(invoice__isnull=False).aggregate(Sum('amount'))["amount__sum"]
+        if (x==None):
+            return 0.0
+        return x
+
+    @property
+    def total_payments(self):
+        x=self.payments.all().aggregate(Sum('amount'))["amount__sum"]
+        if (x==None):
+            return 0.0
+        return x
+
+    @property
+    def balance_due(self):
+        return self.total_invoices - self.total_payments
+
+    def __unicode__(self):  return u'%s' % (self.site.name)
+
+class Invoice(PlCoreBase):
+    date = models.DateTimeField()
+    account = models.ForeignKey(Account, related_name="invoices")
+
+    @property
+    def amount(self):
+        return str(self.charges.all().aggregate(Sum('amount'))["amount__sum"])
+
+    def __unicode__(self):  return u'%s-%s' % (self.account.site.name, str(self.date))
+
+class UsableObject(PlCoreBase):
+    name = models.CharField(max_length=1024)
+
+    def __unicode__(self):  return u'%s' % (self.name)
+
+class Payment(PlCoreBase):
+    account = models.ForeignKey(Account, related_name="payments")
+    amount = models.FloatField(default=0.0)
+    date = models.DateTimeField(default=datetime.datetime.now)
+
+    def __unicode__(self): return u'%s-%0.2f-%s' % (self.account.site.name, self.amount, str(self.date))
+
+class Charge(PlCoreBase):
+    KIND_CHOICES = (('besteffort', 'besteffort'), ('reservation', 'reservation'), ('monthlyfee', 'monthlyfee'))
+    STATE_CHOICES = (('pending', 'pending'), ('invoiced', 'invoiced'))
+
+    account = models.ForeignKey(Account, related_name="charges")
+    slice = models.ForeignKey(Slice, related_name="charges", null=True, blank=True)
+    kind = models.CharField(max_length=30, choices=KIND_CHOICES, default="besteffort")
+    state = models.CharField(max_length=30, choices=STATE_CHOICES, default="pending")
+    date = models.DateTimeField()
+    object = models.ForeignKey(UsableObject)
+    amount = models.FloatField(default=0.0)
+    coreHours = models.FloatField(default=0.0)
+    invoice = models.ForeignKey(Invoice, blank=True, null=True, related_name="charges")
+
+    def __unicode__(self):  return u'%s-%0.2f-%s' % (self.account.site.name, self.amount, str(self.date))
+
+
+
+