Visit My Boost or use the BoostOne app to change your plan.
If you upgrade your plan during the middle of your billing cycle, you'll be charged the difference in price between your old plan and the new upgraded plan. Any changes in service will take effect immediately. Note that any data used on your old plan will be deducted from the data allotment of your new plan. Your data will replenish to the full amount at the start of your next billing cycle.
If you downgrade your plan or remove an extra, the change will take effect on your next billing cycle.