Rent = 15,600 (300x52), Interest = 5% x 315k = 15,750.
costs approx 1.5% of market value = 5,250(estimated, includes agents fees, vacancies, rates, insurance, repairs)
Assume depreciation = 0
Tax loss 5,400.
After tax (assuming 'high income earner' means >185k) = 53.5 x 5,400= 2,889...