Here is the supporting docs that I submitted with my completed PAN card application to them. This is what was needed for mailing the received PAN card back to me in US. Once the PAN card is processed by the Indian government, it is sent to NRI Invest who then will mail it to you in the US. For mailing to you at an address in India, it is slightly different. Anyway for mailing to US:
1. Proof of ID: Copy of my US passport pages that has my photo and ID details.
2. Copy of my OCI card: Info page with photo, address, father's name.
3. If your OCI card
does not have your most current address, they also ask for a copy of your latest US bank statement with current address and this has to be attested by the bank. I did not need the bank statement in my case.
4. You need two color photos for this application form and these are both stuck on the first page of the application. Note that the size of the photos here are not the US passport or India passport standards but are the PAN card specific size (2.5cm x 3.5cm). The instructions say to attach whatever is the standard passport size in your current country but the US passport size is awkwardly big for this application. So I happily used the
ePassportPhoto website to generate a PAN card size passport sheet jpeg file that I took and printed out at my local CVS for like 25 cents
Beyond these docs and photos, the rest is just following the application filling instructions carefully. They provide a sample filled up application which was good but I found some minor discrepancies that I got clarified. Also they also ask you to send a second blank application with just your signature at the last page. This is in case there was something wrong with your actual application form and they would redo it in Delhi on your behalf. I did not like the sound of this and did not submit this with my submitted package.