As house prices and interest rates drop, buy-to-let property investment in some neighbourhoods is suddenly looking attractive again.

For the first time in five years, there are places where you can easily buy a house or apartment, rent it out - and cover all your mortgage and property management costs with some money left over.

Quotable Value estimates 46 suburbs across New Zealand offer positive cash-flow returns. They include apartment-dominated inner-city areas such as Grafton, Eden Terrace and Central Auckland, and the Lambton precinct in Wellington.

But they also include lower-income housing suburbs on the fringes of the big cities, such as Mangere, Otara and Albany near Auckland, or Stokes Valley, Wainuiomata and Waitangirua near Wellington.

Neighbourhoods in smaller North Island centres such as Pleasant Heights and Koutu in Rotorua, Flaxmere in Hastings, and Nawton in Hamilton are also profitable. And it is possible to turn a dollar throughout much of the student-dominated southern city of Dunedin.

QV bases its estimates on 6.7 per cent mortgage interest rates and the investor stumping up a 20 per cent deposit. When working out if a property has positive cash flow, QV's Jonno Ingerson says the most important thing is calculating how much income is required to offset the expenses of owning the property - and this will vary from buyer to buyer, depending on their own financial situation.

In all cases, the positive cash flow is to be obtained on cheaper properties: houses, apartments and units that cost between $110,000 and $300,000.

The most attractive deals in the North Island are to be found harbourside in Central Auckland, where an investor can pay an average $175,000 for a unit, then rent it out for $450 a week - or $23,400 a year. After paying a little under $11,000 in mortgage payments, management fees, rates and other expenses, the owner can still make more than $12,000 in a year.

From 2004 to early 2007, rental yields were eroded and positive cash flow property investments disappeared as house values climbed faster than rents. Then that trend reversed and yields slowly began improving.

Downtown Auckland is an extreme example: apartment prices there have been hit harder than other property prices by the combination of the declining market, over-leveraged owners and developers' problems.

But on Thursday, City Sales auctioned five small inner-city apartments, which all sold for prices ranging from $134,000 to $230,000.

City Sales sales director Mike Richards said the new owners would make a healthy net return from renting the units out. "The general public is becoming more aware of the returns from property in the city, and we're seeing a lot of new faces at our auctions," he said.

Last year's sustained drop in property values was the first in a decade and the trend has continued this year. QV's March statistics show a 9.3 per cent decline in national property values over the past year. Gross rental yields across New Zealand are averaging 4.7 per cent.

If the latest cut in the official cash rate prompts a corresponding fall in home loan interest rates, things will look up further for property investors.