When you rely on a provision of the India-US DTAA to reduce or modify what you'd otherwise owe under standard US tax law, the IRS generally wants that position disclosed, not just reflected silently in a lower number on your return. Form 8833 (Treaty-Based Return Position Disclosure) is that disclosure mechanism, required under Internal Revenue Code Section 6114 for a treaty-based position that overrides domestic law.
What counts as a disclosable position
A treaty-based position is one where you're claiming the treaty changes an outcome the Internal Revenue Code would otherwise produce — for example, treaty-based relief on a specific income category, or leaning on the treaty's residency tie-breaker article when you'd otherwise be treated as a dual resident. Not every treaty-related claim requires the form; the instructions carve out specific routine situations from the disclosure requirement, so it's worth checking the current Form 8833 instructions for whether your particular claim is one of the exceptions before assuming you need to file it.
The penalty for skipping it
Failing to file a required Form 8833 carries its own penalty — currently $1,000 for an individual — and notably, that penalty applies even if the underlying treaty position was completely valid and correctly reduced your tax. In other words, this isn't a penalty for claiming the wrong benefit; it's a penalty for claiming a real benefit without the paperwork that says you're claiming it. The IRS can waive it for reasonable cause, but that's a case made after the fact, not a substitute for filing on time.
Form 8833 is a disclosure, not a calculation — it doesn't replace working out the treaty relief amount itself. The DTAA relief estimator on this site's DTAA & Tax Residency page walks through the credit-method math for a given income and foreign tax paid; whether that specific position also triggers a Form 8833 filing obligation depends on the treaty article involved and is worth confirming with a preparer familiar with treaty disclosure rules.