Utah part-time resident tax return calculation question (moved from Texas, which has no state tax)

There are several issues that need to be understood.

1. If there is one W-2 and you never submitted a state W-4, then the boxes 15-20 will be blank because nothing was withheld for state income taxes. Note if this is the case you will need to send in a Utah W-4 so that your 2020 taxes aren't a disaster.

2. If you only have one W-2 and a Utah W-4 was submitted then boxes 15-20 should have numbers related to how much was withheld and sent to Utah. Note that this only reflects the numbers since the Utah w-4 was submitted, and might not match the actual split between Utah and Texas.

3. If there are 2 W-2 forms because there were two employers, then the 2nd W-2 should have your Utah numbers in boxes 15-20.

I was under the impression that I pay 3 months worth of Utah state tax. After entering all the information, it tells me my Utah taxable income is equal to my total earnings of the year, as reflected in Box 1 of the W-2.

Your part-year resident tax form should reflect the income you had while living/working in Utah. The fact that the tax software thinks that your taxable income is equal to the number in Box 1, tells me that you have either missed the numbers in boxes 15-20, or they are blank and the software is assuming that you only had income in Utah.