Unpaid council tax has long been a burden on local authorities. Last year, ITV news reported that Neath Port Talbot CBC had £4,336,360 outstanding, the fifth highest out of the twenty-two authorities in Wales.
Non-collection of council tax attracts more unwelcome attention, but Neath Port Talbot has trouble with business rates, too. (Technically, these are National Non-Domestic Rates, or NNDR for short - Powys CC provides a useful explanation.) There are at least half-a-dozen viable businesses in Neath town centre which are not shown as paying NNDR on the schedules published on the county borough's own web-site, while appearing on the official rating list (to query what a premises should be paying in NNDR, go to https://www.tax.service.gov.uk/view-my-valuation/cca/search.).
This failure may be seen as victimless as regards Neath, seeing that the money is not retained by the county borough but goes to the government for redistribution. However, not only does the shortfall have to be made up in other ways, but it is also unfair on competing businesses in the town who honestly stump up their business rates.
It could be, of course, that the records are incomplete: NNDR has been paid but has not been recorded. If so, I apologise to the county borough's officials, but would query whether "Freedom of Information" really means what it says if the published data are wrong.