What should I do with my 401(k) balance if I'm returning to India for good?

You have three main paths. First, leave it invested in the US plan or roll it to a US IRA and let it grow until retirement; the account can stay in the US even after you become an Indian resident, and this preserves tax deferral. Second, roll a traditional 401(k) to a Roth over low-income years to lock in tax treatment, though that triggers US tax now. Third, cash it out, which is usually the worst option because of US income tax plus a 10% early-withdrawal penalty if you're under 59½, and 401(k) distributions to a nonresident are subject to US withholding. Most cross-border planners suggest keeping the money in the US wrapper and drawing it in retirement. Compare scenarios with the Return to India Calculator at wealthserene.com/tools/return-to-india.