Those of you who have a Project Fi group plan might have been frustrated by finding that your promotional credits couldn't be used to bring the cost of your overall bill down. Thankfully, that's now changing as Google is letting users share credits with other group plan members.
A verified Project Fi Googler took to Reddit to announce the good news, and this support page backs it up. If you've already opted into Fi credits, you shouldn't have to do anything else and sharing should already be possible. Otherwise, an email should be coming your way explaining how to turn credit sharing on, just as below:
To turn credit sharing on or off:
Go to Billing.
Under Payment Settings, select Fi Credit.
Once set up, Fi credits (from trade-ins and promotions) will be used against your group bill. If the credit exceeds your bill, it'll then carry over into your next one, which is also good to know.