The modified AGI limits are different for the spouse participating in the workplace retirement plan and the spouse who does not. For 2018, although you might not be eligible for a deduction for your own IRA contribution because MAGI is above $121,000, if MAGI is $189,000 or below, your spouse is eligible for full deduction for your spouse's IRA contribution. If MAGI is $199,000 or more, no deduction is permitted. Between MAGI of $189,000 and $199,000 your spouse is eligible for a partial deduction.
https://www.irs.gov/retirement-plans/plan-participant-employee/2018-ira-contribution-and-deduction-l...
