When filing part year resident returns for NY and NJ are Wages and other income pro rated for the period while a NY resident and NJ resident?

[itonewbie]

Yes and no.

Income received while resident is not prorated but if any part of that income is sourced to another state (e.g. bonus received while resident of one state but attributable to services performed in another), a credit may be claimed for taxes paid to the source state.

The flip side of the coin is that income attributable to the other state but received while a nonresident will still be sourced to the other state and taxable to that other state.  Same example, the portion of bonus related to serviced performed in the former state of residence but received after the relocation will generally still be taxable to the former state of residence.

In other words, the total amount of income taxable to both states can exceed what your client actually received because of double taxation but the effect of that may be alleviated by means of credit for taxes paid to other states.