Both forms deal with the substantial presence test, but they do different jobs.
| Form 8843 | Form 8840 | |
|---|---|---|
| Purpose | Explains the basis for excluding days of presence | Claims the closer connection exception |
| Used when | You are an exempt individual, or could not leave because of a medical condition | You meet the substantial presence test but have a closer connection to a foreign country |
| With a return | Attach to your income tax return | Attach to your income tax return |
| Without a return | Send to the address in the form instructions by the return due date | Send to the IRS service center in the form instructions |
| If late | Days cannot be excluded unless you show by clear and convincing evidence that you took reasonable actions and significant steps to comply | The exception cannot be claimed unless you show the same |
Which days each form covers
Form 8843 covers days excluded as an exempt individual and days excluded for a medical condition; see days that do not count. Form 8840 does not exclude days. It lets you be treated as a nonresident for the year even though you meet the test.
Both can matter in the same year. Days excluded on Form 8843 reduce the count before you decide whether you need the closer connection exception at all.
Updated: November 4, 2026