Unable to use commercial software for self-assessment tax return (non-UK resident)

I’m a non-UK resident but I own a letting property in the UK and that’s why I have to submit the self-assessment tax return. Since I’m not qualified to file the tax return online, I tried use one of the commercial softwares. I filled in all the information but when I came to the final step of submission, the authentication of HMRC credentials failed. I am unable to submit the forms. The software company replied that I must register the HMRC online account and activate the self-assessment service in order to proceed with my tax return submission. The software is unable to submit the tax return without my HMRC credentials. In fact, I got the UTR number after my NRL1 application had been approved. I also registered the government gateway ID and I have already set the password in Jun. As I haven’t lived in the UK, I don't have NI number and UK postal code. I couldn’t pass the identity check. I sent a request for activation code for the self-assessment service on 5 Jun and it was sent by post. It took more than a month to arrive and I finally received the activation code on 20 Jul. However, the code has already expired on 5 Jul. That means I can never activate the self-assessment service and even unable to use the commercial software for tax return! The whole story is ridiculous. Does anyone encounter the same problem? HMRC always recommend people to file tax return online or use commercial software. Unfortunately both method do not work for me! The tax return system is not user-friendly to non-UK residents. Now I can only request for paper form. I hope it will safely arrive my home next month.

Hi  I also find the tax return system is not user-friendly, I could not file the tax return online completely as there is one form that I could not file online by using HMRC's system. If I use the commercial software, it requires me to provide the gateway ID and the password to the commercial software provider, May I have ask whether you need to provide the password when you submit the tax return online by using the commerical software system? But the government gateway's page, it always has a warning that we should not share the gateway ID and password to anyone else. I found uncomfortable to provide such password to a third party.

Hi
When submitting the return using the commercial software, you use your government gateway ID and the password associated with that ID to submit the return.

I agree - the system is insane. HMRC try to get people to use the online system and then don't allow for people with non-UK Post Codes. Small hint guys - non resident taxpayers aren't going to have Post Codes in the UK format. When asking for help using email or the online forms, all you get is auto-generated replies that don't solve the problem. A few days ago I spent two hours on the phone to two different HMRC numbers and neither could help me.