IRA / Roth contributions

First: Thank you for your service to our country!

To address your question; there are limitations on how much you can contribute to an IRA (Traditional or Roth).  For 2023, the contribution limit is the LESSER of your compensation or $6,500 ($7,500 if you are age 50 or older).

Compensation generally includes amounts reported in Box 1 of a W2, net earnings from self-employment, taxable alimony and nontaxable combat pay.

If your only income is from a pension and disability, then you are not eligible to contribute to an IRA under the contribution limit rules. 

HOWEVER, if you are married and filing a joint return with your spouse, you may be able to contribute under what is called a Spousal IRA.  You can use the compensation of your spouse to qualify for being able to make contributions to an IRA.  For example, if your spouse is employed and earns $20,000 (box 1 of the W2), then you each can contribute up to $6,500 ($7,500 if age 50 or older).

Remember that there are also Adjusted Gross Income factors you need to be aware of - at a certain amount of AGI, you are no longer able to contribute to a Roth IRA, and whereas there is not an AGI limitation on being able to contribute to a Traditional IRA, there is an AGI limitation on being able to deduct the contribution on  your tax return.