I purchased some office supplies online and received a post-tax "cart discount" (promo savings). How do I enter this discount when recording the expense?

Hello akhet83,

Glad to have you connect with us here. QuickBooks is a powerful program that helps you to manage your accounting with ease. I'll be glad to share more info so you're on the right track with your work. 

Recording your transactions the right way is essential for ensuring your books remain accurate. That said, I recommend consulting an accounting specialist for expert advice. This ensures your entries are recorded in a way that allows for you to navigate the program with peace of mind. You can get in touch with an accounting professional using this link here. Other accounting professionals are able to see this post in the Community and this will allow them to chime in. 

Let me know if this info helps. I'm here to steer you in the right direction.