diff --git a/facho/fe/model/__init__.py b/facho/fe/model/__init__.py
index e1d895c..5f6d6a8 100644
--- a/facho/fe/model/__init__.py
+++ b/facho/fe/model/__init__.py
@@ -111,13 +111,17 @@ class TaxSubTotal(model.Model):
     tax_amount = fields.Many2One(Amount, name='TaxAmount')
     tax_category = fields.Many2One(TaxCategory)
 
-    percent = fields.Virtual(setter='set_percent')
-
-    def set_percent(self, name, value):
-        self.tax_category.percent = value
-        # TODO(bit4bit) hacer variable
-        self.tax_category.tax_scheme.id = '01'
-        self.tax_category.tax_scheme.name = 'IVA'
+    percent = fields.Virtual(setter='set_category')
+    scheme = fields.Virtual(setter='set_category')
+    def set_category(self, name, value):
+        if name == 'percent':
+            self.tax_category.percent = value
+            # TODO(bit4bit) hacer variable
+            self.tax_category.tax_scheme.id = '01'
+            self.tax_category.tax_scheme.name = 'IVA'
+        elif name == 'scheme':
+            self.tax_category.tax_scheme.id = value
+            
     
 class TaxTotal(model.Model):
     __name__ = 'TaxTotal'
@@ -186,6 +190,8 @@ class Invoice(model.Model):
     lines = fields.One2Many(InvoiceLine)
     legal_monetary_total = fields.Many2One(LegalMonetaryTotal)
 
+    cufe = fields.Virtual()
+
     @fields.on_change(['lines'])
     def update_legal_monetary_total(self, name, value):
         for line in self.lines:
diff --git a/facho/model/__init__.py b/facho/model/__init__.py
index 59b8d55..a6689c2 100644
--- a/facho/model/__init__.py
+++ b/facho/model/__init__.py
@@ -50,7 +50,9 @@ class ModelBase(object, metaclass=ModelMeta):
                 (fun, on_change_fields) = on_change_fields_for_function()
                 for field in on_change_fields:
                     obj._on_change_fields[field].append(fun)
-        
+
+
+        obj.__setup__()
         return obj
 
     def _set_attribute(self, field, name, value):
@@ -141,4 +143,8 @@ class Model(ModelBase):
         """
         return value
 
+    def __setup__(self):
+        """
+        Inicializar modelo
+        """
         
diff --git a/tests/test_model.py b/tests/test_model.py
index 7104920..7dc5ef8 100644
--- a/tests/test_model.py
+++ b/tests/test_model.py
@@ -506,3 +506,15 @@ def test_field_amount():
 
     assert '<Line amount="33"/>' == line.to_xml()
         
+
+def test_model_setup():
+    class Line(facho.model.Model):
+        __name__ = 'Line'
+
+        amount = fields.Attribute(name='amount')
+
+        def __setup__(self):
+            self.amount = 23
+
+    line = Line()
+    assert '<Line amount="23"/>' == line.to_xml()
diff --git a/tests/test_model_invoice.py b/tests/test_model_invoice.py
index 79d3604..c7355d9 100644
--- a/tests/test_model_invoice.py
+++ b/tests/test_model_invoice.py
@@ -36,5 +36,8 @@ def _test_simple_invoice_cufe():
     line = invoice.lines.create()
     line.quantity = 1
     line.price = 1_500_000
-    subtotal = line.taxtotal.subtotals.create()
-    subtotal.percent = 19.0
+    line_subtotal = line.taxtotal.subtotals.create()
+    line_subtotal.percent = 19.0
+    line.subtotal.scheme = '01'
+
+    assert invoice.cufe == '8bb918b19ba22a694f1da11c643b5e9de39adf60311cf179179e9b33381030bcd4c3c3f156c506ed5908f9276f5bd9b4'