I agree w/ LuasP - unless you are an EU citizen, you see, tp be planning to include things they do not ask for, and that just complicates things and could slow it down.
Read the checklist on the last page of Form 8 very carefully.
- "If you are an E.U. citizen for more than five years please submit..."
"If you are an E.U. citizen less than five years please submit..."
Regardless, this is in the list at the top of the page that applies to everyone:
- "Copy of documentation from Revenue Commissioners regarding tax affairs if employed."
If you are a PAYE employee that means copies of P21's - available from Revenue. If you are self-employed, there's another form to get (I'm PAYE so I only know about P21's).
From what I've gathered, they may want more than just the one P21 for the year prior to application, so it may be good practice to get all the past ones you can get (they only go back so far), and then request one every year from now on.
I had P21's for 2003-2008. My immigration officer advised me to include all of them at the outset.
I live in a small town and have a very nice, approachable, accessible immigration officer. If you have similar, s/he may be your best source of information.
Wishing you the best of luck.