Mike In Fairley and Moore (NSW Flora) no subspecies for Acacia terminalis are mentioned. It grows just past Tarago along the Nerriga Rd. I would suggest what Jo said Acacia terminalis only.
Australian Plant Name Index says "APC Comment Several subspecies are informally recognised, but none has been validly described." and also says doubtfully naturalised in ACT (though there don't seem to be Atlas of living Australia records. PlantNet gives a key for some subspecies including subsp. angustifolia which is synonym of subsp. Glabrous form (M.Hancock 94) NSW Herbarium. I think it has to be left to the botanists and needs a Herbarium identification. I have a specimen but the flowers are not the best.