Bangkok Net Rental Income Scenarios

The calculation is built around one clearly defined example, not a Bangkok-wide yield. The unit is a 30 sqm one-bedroom condo at The Base Sukhumvit 77. PropertyHub showed several 30 sqm rentals in the project at THB 13,000–15,000 per month in September 2026; the model uses THB 15,000. A separate current sale listing for a 30 sqm unit was asking THB 2.99 million. Those are listing inputs, not evidence that the two ads describe the same apartment or that either figure will become a signed transaction.

The capital base is therefore deliberately transparent. The THB 2.99 million asking price is combined with two editable assumptions: THB 60,000 for buyer-side acquisition costs and THB 50,000 for initial setup, giving THB 3.10 million of full invested capital. An owner modelling an actual purchase should replace all three lines with the amount paid and the costs that were genuinely necessary to make the unit rentable.

Bangkok-wide portal data is useful only as context. FazWaz currently displays a median asking rent of THB 27,900 a month across Bangkok condos, but that figure spans very different districts, sizes and product types. It should not be imported into a unit-level model, and it says nothing about how many months an individual owner will collect rent.

Some inputs are sourced; others are assumptions by design. The rent and sale price come from current project listings. A public project page reports a common-area fee of THB 30 per sqm per month, which is used here only until a juristic-person invoice is available. Management, buyer costs, setup and the reletting/repair reserve remain model assumptions and are shown as such.

The first overstatement usually happens before any complicated calculation: THB 15,000 is multiplied by twelve and THB 180,000 is treated as annual rent received. That number is valid only if twelve payments are actually collected. A listing can support the advertised monthly rent; it cannot prove a signed lease, continuous occupancy or money in the owner's account.

Paid months are therefore an explicit scenario input. Twelve paid months produce THB 180,000 of collected rent, eleven produce THB 165,000 and ten produce THB 150,000. If the unit has an operating history, the history should replace these assumptions: lease start and end dates, missed payments and any periods with no rental income.

A lost month can have different causes. Tenant turnover, owner use and post-tenancy repairs all reduce collected rent, but they do not describe the same operating problem. Keeping those causes separate helps an owner decide whether the issue is leasing, personal use or maintenance rather than hiding all three behind one occupancy percentage.

The number of listings on a portal is not an occupancy dataset. The 12/11/10-month cases below are sensitivity scenarios, not probabilities for Bangkok.

All three rows keep the same THB 15,000 monthly rent, an assumed management fee of 8% of rent collected, THB 10,800 a year of common-area charges, an assumed THB 15,000 reletting/repair reserve and THB 3.10 million of full invested capital. Only paid months change.

The model deducts only costs that are shown as separate lines. A public project page for The Base Sukhumvit 77 reports a common-area fee of THB 30 per sqm per month, which gives THB 10,800 a year for a 30 sqm unit. That is adequate for an illustration, but a real owner's juristic-person invoice and condominium rules take priority because special assessments and charging rules can differ.

Management is set at 8% of rent actually collected. It is an editable assumption, not a claim about the Bangkok market. A real agreement may use a fixed fee, a percentage on a different base or a separate tenant-placement charge; the cash model has to follow the contract and must not stack alternative fee structures as if all of them applied.

The example also carries a THB 15,000 annual allowance for reletting and repairs. This is a reserve, not a documented bill. Once the owner has actual maintenance and turnover records, those numbers should replace it. A single appliance replacement can easily make this line larger than a small difference in headline rent.

Insurance, land and building tax, and owner-paid utilities are not given zero values here. They are excluded from the numeric example because there is no unit-specific policy, tax assessment or lease showing who pays them. If they apply to the selected condo, they belong in the owner-cost section before the result is treated as complete.

A refundable tenant deposit is not rental income merely because it reaches the owner's bank account. Tax treatment is another layer again: a cash expense paid by the owner and a deductible expense for personal income tax are not automatically the same thing.

Only one input changes across the three rows: paid months. That makes the mechanics visible. Losing one paid month removes THB 15,000 of rent, but it also lowers the assumed 8% management fee by THB 1,200, so annual pre-tax cash flow falls by THB 13,800 rather than the full monthly asking rent.

The operating formula is collected rent minus owner-paid cash costs and explicit model reserves. At eleven paid months, collected rent is THB 165,000. Management is THB 13,200, the common-area charge is THB 10,800 and the reletting/repair reserve is THB 15,000, leaving THB 126,000 before personal income tax.

Yield uses the full THB 3.10 million capital base, not just the listing price. THB 126,000 divided by that capital gives 4.06%. If the actual purchase requires higher transfer-stage costs, furnishing or initial repairs, the denominator rises and the yield falls even when the rental cash flow is unchanged.

Nothing about 4.06% is a promise or a Bangkok market forecast. It is the arithmetic result of the inputs printed beside it. The useful part of the model is that every assumption can be replaced without changing the logic.

Operating break-even starts by separating fixed costs from costs that rise with collected rent. In this model, a paid month contributes THB 15,000 of rent and triggers THB 1,200 of assumed management, leaving THB 13,800 toward fixed annual costs. Those fixed lines total THB 25,800: THB 10,800 of common-area charges plus the THB 15,000 reletting/repair reserve.

THB 25,800 divided by THB 13,800 is 1.87, so roughly two paid months cover the operating costs included in this example. That is not an investment payback period, a target return or a financing calculation. Insurance, a land and building tax assessment, special condominium charges or any other fixed owner cost would raise the threshold.

Personal income tax sits outside the operating model. Thailand's Revenue Department places rental income from property in Section 40(5). Its forms for house and building rental show a 30% standard expense deduction or actual expenses under the applicable rules, which is a tax-base calculation rather than a mirror of the owner's cash ledger.

Withholding is also not a universal extra cost of 5%. The Revenue Department's general PIT page lists 5% for rents in its summary of some withholding categories and explains that tax withheld is creditable against the taxpayer's liability. The Revenue Code separately sets different treatment in specific cases, including 15% withholding on Section 40(5) and (6) payments to a non-resident. A flat 5% deduction in every rental scenario would therefore be misleading.

An after-tax scenario becomes useful only once the owner's status, tax residence, other income, allowances, tax year and withholding credits are known. Until then, pre-personal-tax operating cash flow is the cleaner comparable output.