Hi Dettie, sorry for your loss! I'll respond in case it's helpful to you, but my experience may not be totally applicable to you (but might steer you in the right direction).
As i understand it,
you'll have to submit two separate tax returns for 2025.
These had to be paper forms when i did it (i expect it's still the case).
- One covering the period 1st Jan to your husbands date of death (this will include both of your details/incomes). My wife was the assessable spouse, and i completed this form in my name/PPSN, and included details later in the form of my wife's PPSN and date of death etc.
- Second return covering the period from your husbands date of death to 31st December (this will just be you).
I filled the forms in as best i could, and i also gave a short covering letter explaining what i had done (eg some income my wife received after date of death and where i'd allocated it). I never had any questions from Revenue, and eventually a statement of liability issued quite a number of weeks later.
Unhelpfully you may find that you no longer have access/sight of your husband's incomes that Revenue have on system (which you may need to populate the returns).
I'm not too familiar with the 12S or 12 forms but AI tells me the 12S is for people with very simple tax affairs, which sounds like your situation. If the 12S form includes the appropriate lines to declare all your income sources/credits/expenses, then i'd suggest that should be fine to use. Alternatively you could just fill in the more detailed forms, and there will just be lots of blank/not relevant fields.
Revenue's MyEnquiries service has been extremely poor in recent years with very slow responses, and extremely poor quality of response often not reading/answering the actual question posed. I wouldn't bother to be honest.
I would suggest doing as above, populating whichever form as best you can, give a covering letter saying what you've done, and leave them to it. If they've an issue, they'll get back onto you no doubt.
If the above sounds too confusing/complicated, i'd suggest setting up an appointment with Revenue where you can sit down with a person and they're extremely helpful and understanding.
This page details the different types of appointments that are available to the public through the Revenue appointment service.
www.revenue.ie
Take care of yourself xx