Late stage pre-IPO stock is usually fairly valued, and very few companies at this stage would consider ISOs (which have somewhat of a tax benefit). Therefore n

Late stage pre-IPO stock is usually fairly valued, and very few companies at this stage would consider ISOs (which have somewhat of a tax benefit). Therefore no hard rule, just run the numbers on an offer-by-offer basis. Depending on your fit and skill set some employer might kick in some premium to tilt the scale in their favor.