Living in UK (NI), working in ROI

I have registered with HMRC as resident in the UK now and my self-employed income will continue to be in the ROI.

My annual tax return will still be submitted to Revenue but I will also need to do the same to HMRC. I understand the HMRC financial year is April to April and that I will get credit for tax paid to Revenue.

How does this work in practice - when will I need to submit the first tax return for April 2019-20 and how will it work thereafter?

My ROI financial year is concurrent with the calendar year - how will this be allowed for for HMRC ?

Thanks in advance.

Wow, a lot of questions here! First things first, paying money to a high-street tax advisor will be absolutely required - no matter how good my advice. Its not that the advice here will be wrong but you may not present the facts the right way.

Here's the questions for you;
1What type trade or profession are you in?
2Do you have any office or special dedicated place from where you organise your trade or profession - if this is in a client's premises tell us this too.
3How many client's do you have? Do your clients regard you as truly self-employed? You invoice them etc? How much control do you exercise over your day to day work?
4Are you registered for taxes e.g. VAT and if so, where? Who prepares these returns? Are you aware of obligations to register for VAT etc?

These are starter questions to set the scene to see if the fsct pattern matches what you say in your opening post. There'll be a lot more q#s to come.