@Custardslices, the article says it was not clear who owned the house. The land registry yielded no information for the county council. So whatever taxes may have been owed (and things in Ireland are different from the UK) may have been paid from some estate or trust account with nobody physically writing a cheque.
That being said, the coroner (iirc) did remark that there are well over 100K derelict houses in Ireland, and there may well be similar scenes inside some of them, especially in the wake of covid. Additionally, it was remarked that the compulsory purchase process is slow and cumbersome.
Nevertheless, a wellbeing check by the gardai should have been carried out at the smallest whiff of a strange disappearance. They should not have shrugged and assumed he had gone back to England. I think serious questions need to be asked of the gardai in Mallow.
(Also, the post was piled up inside the house, so it was pushed through a mail slot. The house was sited right off the pavement, with no front garden, so any flyers, etc, left halfway in the slot or outside the door could have been blown away ornpushed through by passers-by.)