I have my wife personal allowance as we jointly assessed.
If we opt for single assessed. . She gets 30 a week roughly extra I will lose the equivalent amount in credits.
What's that in cash loss?
I'm high she low rate tax bands thks
There's no net difference, just an allocation between you.
You can ask revenue to split the credits differently since you're both working. Still joint assessment, but your wife uses her own credits.
If it's just her PAYE credits that you have it's just 1650 per year extra tax you'll be paying after separation.
However, you probably have some of her tax band also, so once you're singly assessed you'll start paying high rate a little earlier.
Best thing is to put your salary details into an online calculator as a single person, and see what your tax should be compared to what you pay. I use the Deloitte one, but there are others http://services.deloitte.ie/tc
There are details on Revenue about treatment in year of separation that might help: [broken link removed]