Index: bank.py
===================================================================

--- ./modules/bank/bank.py
+++ ./modules/bank/bank.py
@@ -1,5 +1,7 @@
 #This file is part of Tryton.  The COPYRIGHT file at the top level of
 #this repository contains the full copyright notices and license terms.
+from stdnum import iban
+
 from trytond.model import ModelView, ModelSQL, fields
 
 
@@ -54,13 +56,57 @@
         super(BankAccountNumber, cls).__setup__()
         cls._order.insert(0, ('account', 'ASC'))
         cls._order.insert(1, ('sequence', 'ASC'))
+        cls._error_messages.update({
+                'invalid_iban': 'Invalid IBAN "%s".',
+                })
 
     @staticmethod
     def order_sequence(tables):
         table, _ = tables[None]
         return [table.sequence == None, table.sequence]
 
-    # TODO validate IBAN
+    @property
+    def compact_iban(self):
+        return (iban.compact(self.number) if self.type == 'iban'
+            else self.number)
+
+    @classmethod
+    def create(cls, vlist):
+        vlist = [v.copy() for v in vlist]
+        for values in vlist:
+            if values.get('type') == 'iban' and 'number' in values:
+                values['number'] = iban.format(values['number'])
+        return super(BankAccountNumber, cls).create(vlist)
+
+    @classmethod
+    def write(cls, *args):
+        actions = iter(args)
+        args = []
+        for numbers, values in zip(actions, actions):
+            values = values.copy()
+            if values.get('type') == 'iban' and 'number' in values:
+                values['number'] = iban.format(values['number'])
+            args.extend((numbers, values))
+
+        super(BankAccountNumber, cls).write(*args)
+
+        to_write = []
+        for number in sum(args[::2], []):
+            if number.type == 'iban':
+                formated_number = iban.format(number.number)
+                if formated_number != number.number:
+                    to_write.extend(([number], {
+                                'number': formated_number,
+                                }))
+        if to_write:
+            cls.write(*to_write)
+
+    @classmethod
+    def validate(cls, numbers):
+        super(BankAccountNumber, cls).validate(numbers)
+        for number in numbers:
+            if number.type == 'iban' and not iban.is_valid(number.number):
+                cls.raise_user_error('invalid_iban', number.number)
 
 
 class BankAccountParty(ModelSQL):

Index: setup.py
===================================================================

--- ./modules/bank/setup.py
+++ ./modules/bank/setup.py
@@ -21,7 +21,7 @@
 major_version = int(major_version)
 minor_version = int(minor_version)
 
-requires = []
+requires = ['python-stdnum']
 for dep in info.get('depends', []):
     if not re.match(r'(ir|res|webdav)(\W|$)', dep):
         requires.append('trytond_%s >= %s.%s, < %s.%s' %

Index: tests/test_bank.py
===================================================================

--- ./modules/bank/tests/test_bank.py
+++ ./modules/bank/tests/test_bank.py
@@ -10,7 +10,9 @@
 
 import unittest
 import trytond.tests.test_tryton
-from trytond.tests.test_tryton import test_view, test_depends
+from trytond.tests.test_tryton import test_view, test_depends, \
+    POOL, DB_NAME, USER, CONTEXT
+from trytond.transaction import Transaction
 
 
 class BankTestCase(unittest.TestCase):
@@ -20,6 +22,10 @@
 
     def setUp(self):
         trytond.tests.test_tryton.install_module('bank')
+        self.bank = POOL.get('bank')
+        self.party = POOL.get('party.party')
+        self.account = POOL.get('bank.account')
+        self.number = POOL.get('bank.account.number')
 
     def test0005views(self):
         '''
@@ -33,6 +39,48 @@
         '''
         test_depends()
 
+    def test0010iban_format(self):
+        'Test IBAN format'
+        with Transaction().start(DB_NAME, USER, context=CONTEXT):
+            party = self.party(name='Test')
+            party.save()
+            bank = self.bank(party=party)
+            bank.save()
+            account, = self.account.create([{
+                        'bank': bank.id,
+                        'numbers': [('create', [{
+                                        'type': 'iban',
+                                        'number': 'BE82068896274468',
+                                        }, {
+                                        'type': 'other',
+                                        'number': 'not IBAN',
+                                        }])],
+                        }])
+
+            iban_number, other_number = account.numbers
+            self.assertEqual(iban_number.type, 'iban')
+            self.assertEqual(other_number.type, 'other')
+
+            # Test format on create
+            self.assertEqual(iban_number.number, 'BE82 0688 9627 4468')
+            self.assertEqual(other_number.number, 'not IBAN')
+
+            # Test format on write
+            iban_number.number = 'BE82068896274468'
+            iban_number.type = 'iban'
+            iban_number.save()
+            self.assertEqual(iban_number.number, 'BE82 0688 9627 4468')
+
+            other_number.number = 'still not IBAN'
+            other_number.save()
+            self.assertEqual(other_number.number, 'still not IBAN')
+
+            self.number.write([iban_number, other_number], {
+                    'number': 'BE82068896274468',
+                    })
+            self.assertEqual(iban_number.number, 'BE82 0688 9627 4468')
+            self.assertEqual(other_number.number, 'BE82068896274468')
+
 
 def suite():
     suite = trytond.tests.test_tryton.suite()