Sorry to butt in on this somewhat old but nevertheless relevant thread, and thank you @Henry_Phillips for bringing it up, but do you think @George1 that becoming 1 part in place of 2, might have a bearing on my increase of social charges from zero to around 1,600 euros over the 2 years 2023 and 2024?
I was more concentrating on the fact that I made an error in including my late wife’s incomes (under S1) was the culprit, and maybe it is, but this thread alerted me to the fact that there might be another reason too.