When you die. Normally if you have income over your standard deduction you need to file a return.
Do you need to file a return?
https://ttlc.intuit.com/community/filing-and-paying-taxes/help/do-i-need-to-file-a-federal-return-th...
IRS Do I need to file? Interactive tool
https://www.irs.gov/help/ita/do-i-need-to-file-a-tax-return
