Do 67 years old, 100% disabled veterans in oklahoma have to pay tax on income?

I'm 67 and a 100% disabled veteran who has a renthouse. I know my government benefits are not taxable. My question is, is there a limit to the additional income I can make before I have to pay tax?

Also, what is the amount of income that income tax is not to be collected on my earnings?

 

Thank You Very Much!