Skip,
   What happened to Mike is exactly what happened to me.  I was given some
bad info about when the tax should be paid.  Someone else later told me it
was due within a year.  I called the Calif. Board of Equalization for
clarification and they confirmed that I was a bit late and owed interest and
a penalty.  The penalty was waived by providing a letter of explanation
about the earlier confusion.
   Here's the interesting part: when I asked about other components that
would be added to the plane later, I was told that there would be no further
taxes due.  I can only guess that they assume you'll buy all of your other
components in California and pay sales tax on them.  The bite really comes
once you're flying and start having to pay property tax on the plane.  They
get you coming and going.
   Skip Slater
   N540ES