I found this on the California Franchise Tax Board web at https://www.ftb.ca.gov/professionals/taxnews/2011/February/Article_4.shtml:
If a taxpayer chooses to defer to 2011 and 2012 and the taxpayer
leaves California in one of those years how is the conversion treated
for California purposes? Similarly, how is the conversion treated if a
nonresident moves into California?
In Legal Ruling 98-3, Taxation of IRA Distributions Rolled Over to a
Roth IRA Followed by a Change of Residence Status, we provided
guidance as to the tax treatment of California residents who converted
a traditional IRA to Roth IRA in 1998 and then change residence during
the ratable period between 1999 and 2001, as well as the tax treatment
of non California residents who converted an IRA to Roth IRA in 1998
and then become California residents in the period between 1999 and
2001. The analysis in this ruling remains applicable to the new deferral rule allowing taxpayers to report the income from the
conversion of a traditional IRA ratably over the two years following
the conversion.
Outbound taxpayers must include in gross income only those portions of
the taxable distribution reportable under the two year rule before
they became nonresidents. Under R&TC section 17952.5 the gross income
of a nonresident does not include qualified retirement income
including income from an IRA, received on or after January 1, 1996.
R&TC 17952.5 prevents the imposition of California tax on the portions
of the IRA distribution recognized after an individual becomes a
nonresident.
California will allow for the proration of the taxpayer's income from
the conversion based upon the number of days a taxpayer is within
California during the two years of the proration. An individual who
makes a rollover contribution from an IRA to a Roth IRA before January
1, 2011 and changes residency in 2011, must include in California
adjusted gross income one half of the taxable portion of the
distribution multiplied by a fraction, the denominator of which is the
total number of days in the taxable year and the numerator of which is
the number of days in the year in which the individual is a California
resident.
If the taxpayer changes residency during the second year, the amount
included in California adjusted gross income for the year of the
change in residency is one half of the taxable distribution multiplied
by a fraction, the denominator of which is the total number of days in
the taxable year and the numerator of which is the number of days in
the year in which the individual is a California resident.