When is a year not a year?

When it's calculated by the Entry and Exit Administration of China's Public Security Bureau, that's when.

A "one year visa" in China is valid for one year less one day - so, each year your due date for renewal moves forward by one day. I can't see any good reason for this. It's just irritating and petty. If there is any reason for it, it's probably to try and catch people out - so that they can be badgered into paying 'spot fines' for inadvertently renewing their visas a day late.

It's quite stressful enough having to renew a visa (and residence registration - although this time that was mercifully uneventful for me) in the week following June 4th, to be without a passport on that unhappy (and, for the Chinese authorities, ultra-anxious) anniversary. I think when I reach the point where the visa has to be renewed on the day itself, that will be my cue to quit this country.