We have a free subscription concept separate from Stripe. When a user signs up for a paid subscription we want to charge them immediately but still honor any remaining free-period.
I know I can use trial period to delay the start of the Stripe subscription, but we wanted to charge immediately to confirm valid credit card details. Is it possible to give a discount on a new subscription instead, to account for the users remaining free-time?
For example, if
I would like to charge them $5 today and immediately begin their subscription in Stripe with a Stripe renewal on the next 1st.
Easiest way to do this is to add an invoice item for the amount you want to charge and set a trial period until you want the renewing charge to occur (so in your example you set a trial_end for the next 1st of month). This will generate an initial invoice with the invoice item and then set your recurring payment as you desire.