Before you buy any rental property, one question decides everything: will it put money in your pocket, or quietly drain it every month? This article shows you how to calculate rental yield and monthly cash flow, read the numbers honestly, and spot deals that only look good on paper. You will finish with a repeatable method you can apply to any listing in under 20 minutes.
Gross yield vs net yield: know the difference
Gross rental yield is annual rent divided by purchase price. If a property costs 2,000,000,000 VND and rents for 10,000,000 VND per month, gross yield is 120,000,000 / 2,000,000,000 = 6%. It is a quick screening number, nothing more.
Net yield is where truth lives. It subtracts real operating costs before dividing by the total capital you put in.
What net yield must include
- Property management fees (if any), typically a share of monthly rent
- Maintenance and repairs, plus a reserve for big-ticket items
- Insurance and recurring property taxes or fees
- Vacancy allowance: assume the unit sits empty part of the year
- All acquisition costs: transfer tax, notary, agent, initial furnishing
A 6% gross yield can easily become 3-4% net once these are honest. That gap is the single most common reason new investors are disappointed.
Cash flow: the number that keeps you solvent
Yield measures return on capital. Cash flow measures survival. Monthly cash flow is rent received minus every cash outgoing, including loan repayment.
If rent is 10,000,000 VND, and your mortgage payment plus fees and reserves total 11,500,000 VND, you are 1,500,000 VND negative every month. The property may still gain value, but you are funding it out of pocket. That is a bet on appreciation, not an income asset. Be clear which one you are buying.
The vacancy reality
New investors budget for 12 months of rent. Experienced ones budget for 10 or 11. Tenants leave, units need repainting, and searches take time. A single two-month gap can wipe out a year of thin positive cash flow.
A real scenario
An investor considers a 1.8 billion VND apartment advertised at 6.5% gross yield (rent 9,750,000 VND/month). She runs net numbers: management and building fees 800,000, maintenance reserve 500,000, vacancy at one month per year (about 810,000 averaged monthly), insurance and misc 200,000. Real net operating income drops to roughly 7,440,000 VND/month, or 89,000,000 VND/year. On total capital of 1.9 billion (including acquisition costs), net yield is about 4.7%, not 6.5%. With a loan, monthly cash flow is slightly negative. She negotiates the price down 8% and only then does the deal turn cash-flow positive. Same property, different decision, driven by the math.
Common mistakes and how to fix them
- Using gross yield to decide. Fix: always run net yield and monthly cash flow before making an offer.
- Ignoring vacancy. Fix: assume at least a few weeks empty per year, more in soft rental markets.
- Forgetting acquisition costs. Fix: add transfer, notary, agent, and furnishing to your capital base, not just the sticker price.
- Trusting the agent’s rent figure. Fix: check actual asking rents for comparable units nearby, not the optimistic quote.
- Confusing appreciation with income. Fix: decide upfront whether this is an income asset or a growth bet, and size the risk accordingly.
Action steps: your 20-minute check
- Get the honest asking price and add estimated acquisition costs.
- Find 3-5 real comparable rents nearby and use the conservative figure.
- List every monthly operating cost and add a maintenance reserve.
- Apply a vacancy allowance of at least 8%.
- Calculate net yield on total capital.
- If financing, subtract the loan payment to get monthly cash flow.
- Reject or renegotiate if the numbers only work under best-case assumptions.
Conclusion and next step
Rental property is a numbers business dressed up as an emotional one. Net yield tells you the quality of the return; cash flow tells you whether you can hold it through a rough patch. Your next step is simple: take one listing you are interested in and run the full 20-minute check today. If it survives conservative assumptions, it is worth a viewing. If it needs optimism to work, walk away.
FAQ
What is a good rental yield?
There is no universal figure. It depends on location, financing costs, and your goal. What matters more is whether net yield beats safer alternatives after risk, and whether cash flow is positive under conservative assumptions.
Should I buy a negative cash flow property?
Only knowingly, as a deliberate bet on appreciation, and only if you can comfortably fund the shortfall for years. Never buy one expecting rent alone to cover it.
How much should I set aside for maintenance?
A common practical rule is a reserve based on the property’s age and condition. Older buildings need more. The key is to reserve something every month rather than being surprised by a large repair.
Does yield or cash flow matter more?
They answer different questions. Yield measures efficiency of capital; cash flow measures monthly survivability. A serious investor checks both before committing.