The filing date always stays the same (ed: Sorry, I meant priority date there) - but, yes, that's my understanding: http://en.wikipedia.org/wiki/Patent_Cooperat

The filing date always stays the same (ed: Sorry, I meant priority date there) - but, yes, that's my understanding: http://en.wikipedia.org/wiki/Patent_Cooperation_Treaty http://en.wikipedia.org/wiki/Patent_Cooperation_Treaty USPTO has a diagram here: http://www.uspto.gov/web/offices/pac/mpep/documents/1800_1842.htm http://www.uspto.gov/web/offices/pac/mpep/documents/1800_184... Under their system, it the whole process (to what they call the national phase) can be 30months - it varies from country to country, but 30 seems to be common. http://www.wipo.int/pct/en/texts/pdf/time_limits.pdf http://www.wipo.int/pct/en/texts/pdf/time_limits.pdf