Full after-tax cash flow modelling for NZ residential rentals, incorporating the 100% interest deductibility restored on 1 April 2025, chattels depreciation, ring-fencing of losses, and current 2026/27 tax brackets. Pairs rental economics with mortgage mechanics to show your true monthly position after tax.
A common confusion: tax profit is NOT the same as cash flow. Mortgage interest is a deductible expense, but principal repayments are not. Conversely, depreciation is a deductible expense but no actual cash changes hands. This calculator shows both views side by side.
Even with 100% interest deductibility restored, rental losses are ring-fenced. This means:
Deductible: council rates, insurance (building + landlord), property management fees, advertising for tenants, repairs and maintenance (not improvements), accountant fees, legal fees for leases, travel to inspect property, utilities you pay, chattels depreciation, body corporate fees for investment properties.
NOT deductible: principal repayments on mortgage, capital improvements (extensions, new deck - add to cost base), purchase-related legal fees (cost base), private use portion, your own labour on maintenance.
Cash flow projections are indicative only. Actual results depend on interest rate changes, vacancy, maintenance surprises, and tax law. Most investors find year 1-5 cash flow is negative even at healthy yields - the rationale is typically long-term capital growth, not current cash return.
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