I just got off the phone with Verizon and was offered a $30 monthly military credit. I am on the older Unlimited plan that already includes a 15% discount. They confirmed that the $30 credit is stacked with the 15% discount. I was a bit wary due to my experience with T-Mobile so I had them note it in their system as well.
The credit applies to the Unlimited plans. From my understanding, the credit amount is as follows:
$25 for 2 lines
$30 for 3 or more lines
Edit: I added a screenshot to show the discounts