I came across this thread while looking into sticker expiration for the sake of a work assessment. Even though it's very old now, this thread is a high result when googling CVOR expiration. The problem is the thread is full of misinformation.
hwybear wrote: ↑Tue Jul 19, 2011 6:12 pm "end of the twelfth month after the month of inspection"
If the month of inspection is sometime in July 2010, the month after the month of Inspection is August 2010. Then expiring at the end of the 12th month = August 31st, 2011.
HTA OREG 611:
"An annual inspection sticker described in subsection (4) is valid until the end of the twelfth month after the month of inspection indicated on the sticker"
The twelfth month after the month of inspection is the same month the following year. That is, the twelfth month after the month of inspection (July) is the same month (July) of the following year. For some reason, hwybear in the quoted text is interpreting the inspection requirement as saying, "the twelfth month after the month after the month of inspection" rather than, "the twelfth month after the month of inspection"
I'm not sure why this thread comes up highly on google, but it really shouldn't.