What if I don’t use all of it — does it roll over?

Unused allowance rolls over up to one month's worth, so allowance plus rollover never exceeds two months at once.

Yes, up to one month’s worth. At each monthly reset, whatever you didn’t use — rollover included — carries forward, capped at one month’s allowance, so allowance plus rollover never exceeds two months at once. Anything above that cap is forfeited — a deliberate limit so a quiet period can’t build into an unexpectedly large bank. Rolled-over dollars are spent first.

Good to know: the cap follows your plan. A downgrade trims both buckets to the new plan’s monthly amount when it applies, and an upgrade carries your unused allowance over as rollover, up to one month of the new amount.