CASE STUDY
A Singapore Housing Market Analysis
Executive Summary
| Key FindingIn Singapore’s structurally supply-constrained housing market, the mortgage rate lock-in effect is amplified by HDB resale dynamics, TDSR regulations, and the near-absence of distressed selling. Between 2022 and 2025, private residential resale volumes fell by an estimated 28%, while median prices rose 14% — a paradox explained significantly by lock-in behaviour among homeowners who secured ultra-low fixed-rate packages during 2020-2021. |
This case study adapts the theoretical framework of Katz (2026) — originally developed in the US context — to Singapore’s unique housing market architecture. Singapore presents a particularly instructive comparative case: a highly regulated, dual-track market (public HDB and private) where government policy, land scarcity, and cultural homeownership norms interact to produce lock-in dynamics that are in some ways more severe, and in others structurally different, from those observed in the United States.
1. Background: Singapore’s Housing Market Architecture
1.1 The Dual-Track System
Singapore’s residential market is bifurcated into the public Housing Development Board (HDB) segment, which houses approximately 78% of the resident population, and the private residential market. This structure creates unique lock-in dynamics absent in most comparable economies.
In the HDB segment, resale flat prices are partially insulated from pure market forces due to eligibility restrictions, income ceilings, and the Minimum Occupation Period (MOP) — currently five years — which legally prevents owners from selling or subletting their flats until the MOP is fulfilled. This institutional constraint is itself a form of mandatory lock-in, layered atop the financial lock-in that is the subject of Katz’s analysis.
| Market Segment | Share of Residents | Lock-In Mechanism | Mobility Constraint |
| HDB (BTO/Resale) | ~78% | MOP + financial rate lock | 5-year mandatory hold |
| Private Residential | ~22% | Financial rate lock + ABSD | Additional buyer stamp duty on repeat purchases |
| Executive Condominiums | Mixed | MOP + hybrid pricing | 5-year MOP + 10-year privatisation |
1.2 The Rate Environment: 2020 to 2024
Singapore’s mortgage rates are benchmarked primarily to SORA (Singapore Overnight Rate Average), which replaced SIBOR as the key floating-rate reference in 2021. During 2020-2021, 3-month compounded SORA fell to near zero (0.05%–0.19%), enabling banks to offer fixed-rate packages in the range of 1.0%–1.5% for 2- to 3-year terms. These packages attracted significant uptake among both HDB and private property buyers.
By mid-2023, SORA-linked floating rates had risen to approximately 3.6%–4.0%, and fixed-rate packages were being marketed at 3.8%–4.5%. Homeowners who locked in at 1.2%–1.5% in 2020 thus faced a stark choice upon their package’s expiry: reprice to a substantially higher rate, or sell and exit the market.
| The Singaporean Lock-In CalculusA homeowner with a $1.2M mortgage locked at 1.3% (monthly payment: ~$4,600) repricing to 4.0% would face monthly payments of ~$6,300 — a 37% increase. Selling and re-entering the market as a buyer offers no relief, as new mortgages carry the same elevated rates. For many, especially those approaching retirement, the rational choice is to remain in situ. |
2. Scenario Analysis: Who Gets Locked In?
Scenario A — The HDB Upgrader Who Holds Back
The HDB-to-private upgrading pathway is a well-documented feature of Singapore’s residential market. Typically, households who purchase a Build-to-Order (BTO) flat, complete their MOP, sell the flat at a resale premium, and use the proceeds plus CPF savings to purchase a private condominium.
Mr. and Mrs. Tan purchased a 4-room BTO flat in Tampines in 2017 for S$320,000. By 2022, its estimated resale value was S$580,000. Having completed their MOP, they were positioned to upgrade. However, they had also refinanced their HDB mortgage in 2021 to a fixed bank loan at 1.2% — providing monthly savings that encouraged them to remain. With private condo prices rising and new mortgage rates exceeding 4%, the upgrading premium became prohibitive.
Their decision to hold back removed a unit from the HDB resale supply while simultaneously withdrawing a prospective buyer from the private market. The net effect is a bilateral contraction: one fewer HDB resale listing and one fewer private condo buyer — exactly the supply compression mechanism Katz identifies.
Scenario B — The Investor Who Doesn’t Exit
Singapore’s private residential market has a significant investor segment, historically active in selling upon lease renewal or at the peak of a price cycle. Under the ABSD regime, selling and re-entering incurs substantial tax friction — 20% ABSD for Singapore citizens purchasing a second property as of 2023.
Ms. Lim, a private investor holding a 2-bedroom unit in District 15, planned to sell in 2022 and redeploy into a newer development. Her refinanced mortgage at 1.4% (2020 vintage) meant her monthly carrying cost was low. Selling would require paying off the mortgage and facing ABSD on a replacement purchase. With rates elevated and ABSD unchanged, she chose to rent the unit instead, removing it from the resale market. This pattern, replicated across thousands of investor-held units, compresses resale supply without adding owner-occupied inventory elsewhere.
Scenario C — The Retiree Who Cannot Downsize
Among Singapore’s ageing population, a growing cohort of asset-rich, income-poor retirees owns large HDB flats or private properties that are economically undersized relative to their current household needs. Downsizing — selling a 5-room flat to purchase a 3-room flat — would rationally release larger units to the market.
However, the lock-in effect operates here through the opportunity cost lens: a 5-room flat owned outright or with a minimal outstanding mortgage generates strong rental income in the current market. Selling means losing that income stream and re-entering a transaction-cost-heavy market (conveyancing, stamp duty, moving costs). The elderly couple in Bishan who might have listed their flat in 2021 instead hold on, suppressing the supply of larger resale flats that young families most need.
3. Quantitative Outlook (2025–2027)
The following projections synthesise data from URA, HDB resale statistics, and MAS monetary policy guidance. They are indicative and intended to frame the structural dynamics rather than serve as precise forecasts.
| Indicator | 2022 | 2023 | 2024 (Est.) | 2025 Outlook | 2027 Projection |
| Private resale volume (units) | ~14,800 | ~13,100 | ~11,700 | ~10,500–11,000 | ~12,000–13,500 |
| HDB resale volume (units) | ~26,035 | ~27,084 | ~26,500 | ~25,800 | ~28,000 (MOP wave) |
| Private resale price index (2009=100) | ~189 | ~199 | ~203 | ~200–208 | ~195–215 |
| 3M SORA (approx.) | 0.5% | 3.7% | 3.5% | 3.0–3.5% | 2.5–3.0% (projected) |
| Average fixed-rate package | 2.8% | 4.2% | 3.9% | 3.5–4.0% | 3.0–3.5% |
3.1 The MOP Wave: A Structural Release Valve
A critical Singapore-specific variable absent from the US analysis is the scheduled MOP expiry wave. A large cohort of BTOs launched in 2018–2020 will reach their MOP between 2023 and 2025. HDB data indicates approximately 25,000–30,000 flats are expected to enter MOP eligibility in this window, representing a substantial potential resale supply injection.
However, the lock-in effect attenuates this release. BTO buyers who also secured low-rate mortgages in 2020–2021 face the same repricing disincentive as private owners. Many will hold rather than sell into a high-rate environment, especially if their intention is to upgrade to private property — an upgrade now significantly more expensive in mortgage terms than it would have been in 2021.
| Critical Forward IndicatorIf SORA falls to the 1.8%–2.2% range by 2026-2027, the lock-in effect will unwind asymmetrically and rapidly. Owners whose packages have already expired and been repriced upward will have no rate differential incentive to hold. This could produce a supply surge concentrated in 2026-2028, with significant price moderation implications — particularly in the OCR (Outside Central Region) private market and the mature-estate HDB resale segment. |
4. Impact Assessment
4.1 Impact on Housing Affordability
The lock-in effect operates as a hidden tax on prospective buyers. When supply is suppressed by owners who have no financial incentive to sell, prices do not reflect the equilibrium that would obtain in a frictionless market. For Singapore’s first-time buyers — particularly those ineligible for BTO (e.g., singles under 35, second-timers) — the resale market is the primary route to homeownership, and its compression is acutely felt.
The affordability implications are regressive. Households with sufficient CPF savings and dual incomes can absorb higher purchase prices; those relying on single incomes or with limited CPF accumulation are progressively excluded. The HDB resale market, nominally the ‘affordable’ alternative to private property, has seen median resale prices in mature estates (Bishan, Queenstown, Toa Payoh) approach and occasionally exceed S$700,000-$800,000 for larger flat types.
4.2 Impact on the Rental Market
One of Katz’s key insights — that locked-in owners who would otherwise have exited to the rental market remain in their homes — manifests in Singapore differently. Here, the relevant effect is that locked-in investors do not sell, but continue to rent out their properties. This actually maintains rental supply, but at higher asking rents, because the investor’s cost of capital (the mortgage) has risen at repricing, and this is passed through to tenants.
Singapore’s rental market saw median rents for non-landed private properties rise approximately 50% between Q1 2021 and Q4 2023, before moderating. A portion of this increase reflects the broader demand surge (foreign professionals, post-COVID normalisation), but the lock-in effect’s contribution is the maintenance of elevated rental pricing as the alternative to selling.
| Stakeholder | Primary Impact | Severity | Timeframe |
| First-time HDB buyers | Compressed resale supply, higher prices | High | 2023–2026 |
| Private upgraders | Dual cost pressure: buy-high, borrow-high | High | 2023–2025 |
| Tenants (private) | Higher rents as investors hold rather than sell | Moderate–High | 2022–2024 |
| Existing homeowners | Trapped by rate differential, reduced mobility | Moderate | 2022–2026 |
| Property developers | Reduced secondary market competition; new sales sustained | Low–Moderate | 2023–2025 |
| Government / HDB | Policy pressure on BTO ramp-up and resale grants | Moderate | 2024–2027 |
4.3 Macroeconomic and Financial Stability Implications
The MAS has noted that household debt remains elevated relative to historical norms, with mortgage debt constituting the largest component of household liabilities. The Total Debt Servicing Ratio (TDSR) framework — capping total debt obligations at 55% of gross income — provides a structural buffer against systemic over-leveraging. However, it also acts as a transmission mechanism for the lock-in effect: homeowners who bought at low rates near the TDSR ceiling face TDSR constraint at higher rates, making simultaneous sale-and-repurchase transactions financially non-viable.
| Systemic Risk NoteUnlike the US, Singapore does not have a significant subprime or adjustable-rate mortgage population vulnerable to payment shock. The TDSR framework and conservative LTV limits (75% for first properties) mean that rate increases create lock-in without creating widespread default risk — a meaningful structural difference from the US context and one that makes the lock-in effect more durable. |
5. Policy Solutions and Recommendations
5.1 Supply-Side Interventions (High Priority)
Consistent with Katz’s conclusion that supply expansion is the most effective affordability lever, Singapore’s policy toolkit has several underutilised instruments:
- Accelerated BTO completion timelines: The government has already committed to shortening BTO wait times from ~5 years to ~3 years for a portion of launches. Expanding this programme to cover a larger share of the pipeline would directly address supply latency.
- Increased land release under the Government Land Sales (GLS) programme: GLS supply in the confirmed list can be calibrated counter-cyclically. During periods of lock-in-induced supply compression, accelerating GLS confirmed list supply creates a pipeline of new private units.
- Voluntary Early Redevelopment Scheme: A targeted financial incentive (e.g., stamp duty rebate or enhanced CPF housing grant) for owners of older HDB flats who voluntarily sell ahead of SERS (Selective En bloc Redevelopment Scheme) could release supply in areas where demand is concentrated.
5.2 Demand-Side Considerations (Secondary Priority)
Demand-side measures are, per the Katz framework, unlikely to resolve the fundamental price-supply imbalance and risk worsening affordability by boosting purchasing power without corresponding supply increases. Nonetheless, targeted interventions have merit:
- TDSR recalibration for owner-occupiers downsizing: Currently, TDSR applies uniformly at repricing. A time-limited TDSR concession for homeowners downsizing (i.e., selling a larger home to purchase a smaller one) would reduce the financial friction of supply-releasing transactions.
- Enhanced resale grants for second-timer HDB buyers: Reducing transaction costs for second-timers purchasing resale flats incentivises the upgrading pathway and unlocks mid-range resale inventory currently held back.
5.3 Market Transparency Measures
The lock-in effect is partly sustained by informational frictions — owners uncertain about post-sale re-entry costs may hold conservatively. The following measures could reduce this friction:
- HDB’s enhanced resale portal already provides price benchmarks; extending this to include expected ABSD, legal, and relocation cost calculators would help owners make more informed sell-or-hold decisions.
- MAS could publish aggregate data on the proportion of outstanding mortgages still within fixed-rate lock periods by vintage year, enabling market participants to anticipate supply unlock events associated with rate resets.
5.4 What Would NOT Work: Mortgage Portability
Katz’s US paper explicitly critiques mortgage portability — allowing homeowners to transfer their existing low-rate mortgage to a new property — as an ineffective policy response. This conclusion applies with equal force in Singapore. Portability would facilitate individual household mobility but would not add a single unit of net housing supply. In a supply-constrained market, it would simply redistribute the same pool of buyers across the same insufficient pool of homes, leaving aggregate prices unchanged.
Singapore’s government has, to its credit, historically focused affordability policy on supply-side levers (BTO expansion, GLS, SERS) rather than financial engineering, and the evidence from this analysis affirms that orientation.
6. Conclusion
The mortgage rate lock-in effect is not merely a US phenomenon — it operates in Singapore with distinctive institutional contours. The MOP regime creates a state-mandated precursor to financial lock-in; the ABSD framework raises the cost of churn; and the TDSR constraint transforms rate increases into mobility barriers for households near the affordability boundary.
What distinguishes Singapore from the US context is not the absence of lock-in dynamics but their durability and structural embeddedness. Without a subprime sector or forced-sale mechanism, the release of locked-in supply will be gradual and policy-dependent rather than market-corrective. The MOP expiry wave of 2023–2025 provides a structural opportunity for managed supply release — but only if households can be induced to act on their eligibility, rather than hold indefinitely behind a wall of financial inertia.
The central policy implication is clear: affordability in Singapore’s housing market will not be restored by financial engineering or demand suppression alone. The lock-in effect is, at its root, a supply problem — and it demands a supply solution.
References & Data Sources
Katz, J. (2026). “The Lock-In Effect and Housing Market Dynamics.” Harvard Joint Center for Housing Studies Working Paper.
Urban Redevelopment Authority (URA). Real Estate Information System (REALIS) — Private Residential Resale Statistics, 2019–2024.
Housing & Development Board (HDB). Resale Flat Prices and HDB Annual Reports, 2019–2024.
Monetary Authority of Singapore (MAS). Financial Stability Review, 2022–2024.
Singapore Department of Statistics. Key Household Income Statistics and Population in Brief, 2024.
Fannie Mae. Home Purchase Sentiment Index, September 2024.