How should I enter the name if someone doesn't have a last name? Since both first name an last name are mandatory fields.

[Filingnow]

The SIN letter states the first name in the last name field and the first name field is blank. I am not able to proceed as both the first name and last name fields are mandatory.

[TurboTaxLise · Accepted solution]

If you are registered with the CRA with only ONE name, then in the last name field put in "Not Applicable" to be able to continue through your tax return.