class MyForm(forms.Form):
    password = forms.CharField(widget=forms.PasswordInput)

def __init__(self, user, *args, **kwargs):
    super(MyForm, self).__init__(*args, **kwargs)
self.user = user

def clean_password(self):
    valid = self.user.check_password(self.cleaned_data['password'])
if not valid:
    raise forms.ValidationError('Password Incorrect')
return valid
check_password() from a user again