Interesting . . . I know of a PR case where the applicant had not filed federal taxes in ten years. The situation was blamed on their spouse and they filed before their hearing. But, I find it difficult to believe that the applicant went ten years without filing and didn’t know. The spouse did contracting work and I don’t know if he was receiving 1099 all those years but the applicant was receiving W-2 wages and those would have been reported to the IRS each year. It seems likely that their mailbox was filled with IRS notices.
The applicant in that case, retained clearance after a hearing.