In the FAQ, it states that receipts are kept online for 12 months. However, about a year ago, I noticed 13 months, then 14, etc., so that now 18 months worth are kept online. It remained 18 months worth for about 9 months or so, and now I notice 19 months of receipts are available. Has Verizon decided they're going to keep 24 months now? In this day and age of data mining, identity theft, etc., if the policy is 12 months then I don't really want to see 19 months of receipts and call records hanging around.
Bills were available for the past 12 months until earlier this year, when they started keeping 18 months' worth available. I haven't seen anything to suggest that they're now changing it to 24 months. My guess is that your oldest bill just hadn't dropped off yet when they posted the newest one.