I moved from UT to CA during the year. My UT state return is asking how much income was double-taxed while a UT resident, and how much CA state tax I paid on it. Where?

[DanielV01 · Accepted solution]

It depends. If you were working in CA while living in Utah, the amount of income you earned in California during that time would be double-taxed income.  However, if you were working in Utah the entire time, there is no double-taxed income.  

If you did work in CA while living in Utah, you may need to do some math.  If you know the exact amount you earned in California during that time, use that figure.  You can then use a percentage to calculate how much CA tax you paid on that income.  To figure out the percentage, divide the portion of California income earned in Utah by your overall California income.  Then, multiply this percentage by the amount of California tax liability (which is tax withheld minus California refund, or plus additional California tax due).  The final result is the CA tax on the double-taxed income.

If you don't know the exact amount you earned in CA while living in Utah, you will use a different percentage to figure that out.  Divide the number of days you lived in Utah in 2016 by 366, the number of days in the year.  Then multiply by your total California income.  This would be the double-taxed income that you may allocate, or designate, to Utah.  You can then figure out the CA tax using the same formula in the paragraph before this one.

The whole purpose behind this is so that you are not overtaxed.  California taxes all of the income you earned while working there, and Utah taxes the portion of income you earned while living in Utah, even if you earned that in California.  So that you are not over-taxed, Utah will give a credit for the tax you pay to California for the income you earn in California while living in Utah, up to the amount of tax that Utah charges on the same income.