@csrf_exempt
def http_notification(request):
    response = HttpResponse(status=404)
    if request.method == 'POST':
        line_notification_options = '%s&%s&%s&%s&%s&%s&%s&%s&%s' % (
            request.POST['notification_type'], request.POST['operation_id'], request.POST['amount'],
            request.POST['currency'], request.POST['datetime'], request.POST['sender'], request.POST['codepro'],
            settings.YANDEX_MONEY_SECRET_WORD, request.POST['label'])
        if request.POST['sha1_hash'] == hashlib.sha1(line_notification_options.encode()).hexdigest():
            YadTransaction.objects.create(
                notification_type=request.POST['notification_type'],
                currency=int(request.POST['currency']),
                operation_id=request.POST['operation_id'],
                amount=request.POST['amount'],
                withdraw_amount=request.POST['withdraw_amount'] if 'withdraw_amount' in request.POST else 0,
                datetime_transfer=dateutil.parser.parse(request.POST['datetime']),
                sender=request.POST['sender'],
                codepro=False if request.POST['codepro'] == 'false' else True,
                label=request.POST['label'],
                test_notification=True if 'test_notification' in request.POST else False,
            )
            lab = request.POST['label']
            aaa = request.POST.get('withdraw_amount')
            moss = Money.objects.get(moneyname=lab)
            moss.moneyvalue += aaa
            moss.save()
            response = HttpResponse(status=200)

Models.py
....
withdraw_amount = models.DecimalField('Сумма, которая списана со счета отправителя', max_digits=12, decimal_places=2, null=True, blank=True)
.......

class Money(models.Model):
    moneyname = models.CharField(max_length=120)
    moneyvalue = models.DecimalField(decimal_places=2 ,max_digits=20)