Last year we had (Non Resident) Out of State income for Iowa, this year it was half as much, but taxes owed are higher. We had to file MFJ this year vs MFS due to IA changes. We also both turned 65 in 2023. Any thoughts?

Without being able to see your return, it is hard to tell why you owe more this year. 

What type of income are you reporting on your IA non-resident return? Did you have any IA Taxes withheld? If you did, make sure you have entered the correct amount.

Although non-Iowa income is used to calculate the initial tax liability at the appropriate tax rate, the non-Iowa income itself is not subject to tax. Only Iowa-source income is taxed.

For information on how does IA tax your Income check, Iowa Department Of Revenue

I recommend that you make a line by line comparison with last year's return to see what is different this year.