diff --git a/facho/fe/form/__init__.py b/facho/fe/form/__init__.py
index aa9ca61..e2a24ea 100644
--- a/facho/fe/form/__init__.py
+++ b/facho/fe/form/__init__.py
@@ -110,7 +110,7 @@ class Amount:
         return formatter % self.float()
 
     def float(self):
-        return round(self.amount, DECIMAL_PRECISION)
+        return float(round(self.amount, DECIMAL_PRECISION))
     
 
 class Quantity:
@@ -279,11 +279,9 @@ class TaxSubTotal:
     tax_scheme_name: str = 'IVA'
 
     tax_amount: Amount = Amount(0.0)
-    taxable_amount: Amount = Amount(0.0)
 
     def calculate(self, invline):
         self.tax_amount = invline.total_amount * Amount(self.percent / 100)
-        self.taxable_amount = invline.total_amount
 
 
 @dataclass
@@ -293,10 +291,11 @@ class TaxTotal:
     taxable_amount: Amount = Amount(0.0)
 
     def calculate(self, invline):
+        self.taxable_amount = invline.total_amount
+
         for subtax in self.subtotals:
             subtax.calculate(invline)
             self.tax_amount += subtax.tax_amount
-            self.taxable_amount += subtax.taxable_amount
 
 
 @dataclass
@@ -409,6 +408,14 @@ class LegalMonetaryTotal:
     payable_amount: Amount = Amount(0.0)
     prepaid_amount: Amount = Amount(0.0)
 
+    def calculate(self):
+        #DIAN 1.7.-2020: FAU14
+        self.payable_amount = \
+            self.tax_inclusive_amount \
+            + self.allowance_total_amount \
+            + self.charge_total_amount \
+            - self.prepaid_amount
+
 
 @dataclass
 class AllowanceChargeReason:
@@ -556,12 +563,7 @@ class Invoice:
             .sum()
 
         #DIAN 1.7.-2020: FAU14
-        self.invoice_legal_monetary_total.payable_amount = \
-            self.invoice_legal_monetary_total.tax_inclusive_amount \
-            + self.invoice_legal_monetary_total.allowance_total_amount \
-            + self.invoice_legal_monetary_total.charge_total_amount \
-            - self.invoice_legal_monetary_total.prepaid_amount
-
+        self.invoice_legal_monetary_total.calculate()
 
     def calculate(self):
         for invline in self.invoice_lines:
diff --git a/facho/fe/form_xml/invoice.py b/facho/fe/form_xml/invoice.py
index 1abece6..9f6bac3 100644
--- a/facho/fe/form_xml/invoice.py
+++ b/facho/fe/form_xml/invoice.py
@@ -435,9 +435,10 @@ class DIANInvoiceXML(fe.FeXML):
         total_tax_amount = Amount(0.0)
 
         for invoice_line in invoice.invoice_lines:
+
             for subtotal in invoice_line.tax.subtotals:
                 tax_amount_for[subtotal.tax_scheme_ident]['tax_amount'] += subtotal.tax_amount
-                tax_amount_for[subtotal.tax_scheme_ident]['taxable_amount'] += subtotal.taxable_amount
+                tax_amount_for[subtotal.tax_scheme_ident]['taxable_amount'] = invoice_line.taxable_amount
                 total_tax_amount += subtotal.tax_amount
                 # MACHETE ojo InvoiceLine.tax pasar a Invoice
                 percent_for[subtotal.tax_scheme_ident] = subtotal.percent
@@ -505,10 +506,12 @@ class DIANInvoiceXML(fe.FeXML):
                                          './cac:TaxTotal/cbc:TaxAmount',
                                          invoice_line.tax_amount)
 
+            #DIAN 1.7.-2020: FAX05
+            fexml.set_element_amount_for(line,
+                                         './cac:TaxTotal/cac:TaxSubtotal/cbc:TaxableAmount',
+                                         invoice_line.taxable_amount)
             for subtotal in invoice_line.tax.subtotals:
-                fexml.set_element_amount_for(line,
-                                             './cac:TaxTotal/cac:TaxSubtotal/cbc:TaxableAmount',
-                                             subtotal.taxable_amount)
+
                 line.set_element('./cac:TaxTotal/cac:TaxSubtotal/cbc:TaxAmount', subtotal.tax_amount, currencyID='COP')
                 line.set_element('./cac:TaxTotal/cac:TaxSubtotal/cac:TaxCategory/cbc:Percent', subtotal.percent)
                 line.set_element('./cac:TaxTotal/cac:TaxSubtotal/cac:TaxCategory/cac:TaxScheme/cbc:ID', subtotal.tax_scheme_ident)
diff --git a/tests/test_form.py b/tests/test_form.py
index 93d03c4..006ce31 100644
--- a/tests/test_form.py
+++ b/tests/test_form.py
@@ -132,3 +132,45 @@ def test_valid_tipo_operacion_nota_credito():
     )
     inv = form.CreditNote(reference)
     inv.set_operation_type('20')
+
+
+def test_quantity():
+    quantity1 = form.Quantity(10, '94')
+    assert quantity1 * form.Amount(3) == form.Amount(30)
+
+def test_invoice_line_quantity_without_taxes():
+    line = form.InvoiceLine(
+        quantity = form.Quantity(10, '94'),
+        description = '',
+        item = form.StandardItem('test', 9999),
+        price = form.Price(
+            amount = form.Amount(30.00),
+            type_code = '01',
+            type = 'x'
+        ),
+        tax = form.TaxTotal(subtotals=[]))
+    line.calculate()
+    assert line.total_amount == form.Amount(300)
+    assert line.tax_amount == form.Amount(0)
+
+def test_invoice_legalmonetary_with_taxes():
+    inv = form.NationalSalesInvoice()
+    inv.add_invoice_line(form.InvoiceLine(
+        quantity = form.Quantity(1, '94'),
+        description = 'producto facho',
+        item = form.StandardItem(9999),
+        price = form.Price(
+            amount = form.Amount(100.0),
+            type_code = '01',
+            type = 'x'
+        ),
+        tax = form.TaxTotal(subtotals=[])
+    ))
+    inv.calculate()
+
+    assert inv.invoice_legal_monetary_total.line_extension_amount == form.Amount(100.0)
+    assert inv.invoice_legal_monetary_total.tax_exclusive_amount == form.Amount(100.0)
+    assert inv.invoice_legal_monetary_total.tax_inclusive_amount == form.Amount(100.0)
+    assert inv.invoice_legal_monetary_total.charge_total_amount == form.Amount(0.0)
+    assert inv.invoice_legal_monetary_total.payable_amount == form.Amount(100.0)
+