Amid the chaotic and action-packed final sitting week of Parliament for 2016, Immigration Minister Peter Dutton quietly added a sixth property to his impressive and expanding portfolio.

With the purchase of an investment property in sunny Townsville, Mr Dutton and his wife Kirilly now have five places for rent, including a $2.3-million, four-bedder on Queensland's Palm Beach, known as "Millionaire's Row", which counts surfing legend Kelly Slater as a resident.

The Duttons have two other properties in the Sunshine State and another in Canberra. Their home is on a two-hectare block at Camp Mountain, north-west of Brisbane, in the senior conservative figure's electorate of Dickson.

The tidy investment portfolios enjoyed by many federal MPs have not gone unnoticed in the context of the fraught debate over negative gearing, which allows property investors to deduct losses from their taxable income.