My neighbor has been asking TAG and the builder who looks after filters. So far it looks like we own the furnace and so will be responsible for maintenance and filters.
She also tried to find filters, as did we. unfortunately, they are an odd size 15x28x1 and regular stores do not seem to carry them. If anyone finds a source please let us know as I am sure many of us would like to replace the current ones now the building is getting a little more settled and the dust is settling.