The OpenSource Accounting Tools We Use: KmyMoney & InvoiceNinja

  1. yes, manual check entry in Invoice Ninja and dumped to KyMymoney. It also can email clients payment confirmation when we input the check which is an option we sometimes use.
  2. They have the ability configure multiple tax rates, but it is done per invoice, not per client.
  3. The system can do partial and slip payments and does have a tax report