A. The NTEE code you use on your Form 1023-EZ will depend on your organization's purposes and activities.  There are, however, definitely some NTEE Codes to avoid:

These NTEE codes usually describe exempt organizations not eligible to form Form 1023-EZ:
A6E, A11, B11, B20, B21, B24, B25, B28, B30, B40, B41, B42, B43, B50, B60, B90, C11, D11, E11, E20, E22, E24, E31, F11, F31, G11, H11, I11, J11, K11, L11, M11, N11, O11,P11, P51, Q11, R11, S11, T11, T23, U11, V11, W11, X11, Y11, Z11

These NTEE codes are popular among non-501(c)(3) exempt organizations:
A01, A02, A03, A19, A80, B83, C32, J40, K20, K26, K28, L50, M24, N50, N60, N61, N99, P20, P99, S20, S30, S40, S41, S46, S47, S50, S80, S81, W30, W60, W61, W80, W99, X03, X50, Y03, Y20, Y22, Y23, Y33, Y40, Y42, Y43, Y44, Y50, Y99, Z99

Note that the Form 1023-EZ software will allow you to continue with the form even if you choose an inappropriate NTEE Code.

Although the Form 1023-EZ instructions suggest visiting https://nccs.urban.org for additional information about NTEE Codes, this page lists every NTEE Code and provides brief descriptions.  The search box at the top of the page will search the whole NCCS site.  To search only the NTEE list, use Ctrl+f.  Enter either a keyword, like "history," to view the definitions of all codes that might apply, or enter a specific NTEE code to view that particular code's definition.

Q. Which NTEE Code should we use?​