For your Utah capital gains, use form number TC40. The Utah state capital gains tax is simple to calculate.The good news is that Utah's tax rate is lower than other states. Federal law requires Americans to pay capital gains tax on real estate profits that exceed certain thresholds. I've written this article to explain Capital Gains tax, how to calculate it and creative ways to reduce or eliminate it. General Information. Use the menu to the left for complete information about Utah sales and use taxes. Taxpayers pay capital gains tax based on the period of ownership and, when selling a personal residence, the length of time lived in the home. Is there anything reasonable in the city for under 600k or am I just being crazy? Salt Lake City taxes can be hard to stay on top of.