Deductible contributions to a self-employed retirement plan also reduce the amount available to support an IRA contribution. If all of your net earnings go to elective deferrals to a self-employed 401(k), nothing is left to contribute to a Roth IRA. In other words, the amount available to support a Roth IRA contribution is Schedule 1 line 3 minus Schedule 1 lines 15 and 16.
Excluded foreign-earned income also will not support an IRA contribution, but I suspect that that is not a factor in this case.
