I purchase groceries and get cash back on my debit card. How do I enter the split so the cash back part goes into my cash account. I can do this with GNUCASH but can't get it to work with KMYMONEY
Thank you.

The cash back is an income. When you create the transaction, enter the net-value as amount. Then start the split transaction editor and enter a first split with your expenses and a second with the cash back income. Use a negative value for income at that point.

I use an asset cash account - e.g., "Cash - Warren" and when splitting the transaction I would enter, for example:

$100.00 in the (total) Amount on the Transaction and on the split editing window:

Category
Food: Groceries $80.00
Cash - Warren $20.00

Thank you. !

Sorry brooklynsenior: wgschaub is right. I would do it the same way. Mixed up the terms cash back and rebate in your request and based my first answer on it. My English skills seem to vanish slowly, I guess