Here's a video that shows how it's done:
If you prefer to read:
To start the process of filing your 1701A, click on the FILE Now button beside the Annual Income Tax Return Card.
You'll then be presented with the following fields:
Each field has a detailed description that should help you determine what to put in each field.
After that, Click on NEXT and a preview of your tax form will be shown. If you're all good, click on Submit, choose your payment method (if there's a payable amount).
Make sure to complete the payment process! Especially if you decide to pay via bank or non-bank OTC.
That's it! :)