How early can I refill a prescription?

There are two clocks, and both decide. The insurance clock: most plans allow a refill when you have used most of your supply, which works out to a few days early on a 30-day prescription, and trying earlier gets rejected as too soon to fill. The legal clock is stricter for controlled substances: the DEA notes Schedule II drugs like oxycodone and Adderall allow no refills at all, so every fill is a new prescription, and early fills on controlled drugs face tighter pharmacy scrutiny everywhere. Practical answers: travel is the legitimate early-fill case, and most insurers have a vacation override the pharmacy can request; order a few days before empty, not at zero, since repeat systems take a couple of working days, as the NHS notes; and weekend and holiday closures argue for planning. If you keep running out early because the dose is not lasting, that is a dose-review conversation with your prescriber, not a refill-timing problem, and rationing pills to stretch a supply is the version to avoid. Ask your pharmacy to set refill reminders or automatic refills where offered, which removes the forgetting variable entirely.