What AO code should I fill in NSDL form?

AO code is based on your location - City/Town/Area, your category (company or otherwise), and your income levels. The following link helps you to find AO for your area and income levels.

Search for AO-Code Details

For the additional details provided in the comments, AO Code for Kolkata is in the link below

AO-Code for PAN Card: KOLKATA

Unfortunately, Kolkata has too many AO codes - 298 in total. It is a bit difficult to find AO if it is for a big city like Kolkata. However, as much as I have checked, the PIN Code and area you have mentioned does not have a specific AO Code. As per wikipedia, your area district headquarters is Barasat. The AO Code for Barasat is in the image below.



Between the two of the codes, you can pick one, based on the first alphabet of your first name.

If you are still not sure, do not bother about the AO Code details. AO Code details are not mandatory if you submit an application at a near by PAN Card Office / TIN Facilitation centre.

Link below helps you to fill a PAN Card Application and download the PDF for free.

Brokerage Free - PAN Services

If you need to find a PAN Card office / TIN Facilitation centre near by, the link below will be of help.

PAN Card Offices - Brokerage Free - PAN Services

Hope the above information is useful.