What happens if I don’t send in Form 8843?

Form 8843, Statement for Exempt Individuals and Individuals Claiming a Medical Condition is required by the regulations to be submitted by all individuals in F, J, M, or Q status who are exempt from counting days for purposes of the substantial presence test (the 183-day residency formula). The form should be attached to Form 1040NR or 1040NR-EZ if you have a return filing obligation. Otherwise, the Form 8843 should be signed and dated and submitted separately.