Don't listen to the half answers from Intuit. Their "support" doesn't understand the product, or the questions being asked. Yes you can save a card on file in QBO and just charge the client later. You add the client, click edit on the client's profile, set the payment method to "Credit Card" and then you get a button to "Enter Card Details". Put in the card info and the client's address and it's now saved on file. When you are ready to invoice the client, simply create the invoice, hit receive payment, select "Credit Card" as the payment method and the card will populate. Sales receipts are similar - just without the receive payment. Create a sales receipt and set the payment method to Credit Card.