CRA Result Code: 21 The Canada Revenue Agency was unable to accept your return, as your NETFILE Access code did not match our records.

Using NAC is not mandatory for Filing . Please remove the Netfile Access Code (NAC) and then try to file.

Thanks for choosing TurboTax.

how do I do that?

@Murray1958 Are you using TurboTax Desktop or TurboTax Online? 

I entered a wrong access code and CRA rejected. how to change it with right one?

@VolodymyrDr It's not a mandatory field, Remove Netfile Access Code and try to Netfile.