99-1 and decoupling: the arithmetic, and where IRAS draws the line

Two things get called the same thing, and they are not the same thing. Decoupling is a part-share transfer out of an existing co-ownership: two people own a residential property as tenants-in-common, one transfers their share to the other, and the outgoing owner is left owning nothing. Their property count for Additional Buyer’s Stamp Duty purposes falls to zero, and they can buy again at the rate for a first property.

The 99-1 pattern is different, and it is the one the Ministry of Finance has described as contrived. In its reply of 21 April 2023, MOF set out the typical shape: a buyer who qualifies for the lowest ABSD rate purchases the property alone, and then, within a very short period of time, sells a 1% interest to another individual with a higher ABSD profile — commonly a spouse or family member. Ad valorem duty on that second step bites only on 1% of the value. Both names go on the title.

1. 01The property is bought in undivided shares

   Tenants-in-common hold separate and distinct shares, equal or wildly unequal — 50-50, 80-20, 99-1. The manner of holding is recorded at purchase.

2. 02One share is transferred

   A transfer of a part share is a chargeable instrument in its own right. BSD is assessed on it, and ABSD too if the transferee’s profile and count attract it.

3. 03Duty is computed on the share, not the property

   IRAS assesses ad valorem duty on the consideration or the market value, whichever is higher, applied to the value of the share transferred. That is the arithmetic the structure turns on.

Nothing in that sequence is unlawful in the abstract. What matters is why the shares were chosen and what happened next.

The rule that makes the outcome so expensive when it goes wrong is that ABSD does not apportion. IRAS puts it in one sentence.

A 1% share and a 100% share do the same work to your count. Own a fifth of a second property and IRAS counts you as owning two. The second rule is the companion to it, and it is the one the 99-1 structure is built to defeat.

So a Singapore citizen buying a first home with a foreign spouse does not pay nil on 50% and 60% on the other 50%. IRAS charges 60% on the whole. Split the purchase into two steps and, on the face of the instruments, 60% falls on 1% of the value instead. The gap between those two numbers is the entire motive, and it is exactly what the Commissioner is directed to look at.

The anti-avoidance provision is section 33A of the Stamp Duties Act 1929. It is short, it is broad, and it is drafted to look through form to substance. Subsection (2) applies where the Commissioner is satisfied that the purpose or effect of an arrangement is, directly or indirectly, one of three things.

Where it applies, the Commissioner must disregard or vary the arrangement and make any adjustment that the Commissioner considers appropriate, including to the amount of duty payable. The obligation is not discretionary once the Commissioner is satisfied. And "arrangement" is defined widely enough to capture the sequence rather than the individual instruments.

That last clause — "all steps by which it is carried into effect" — is the operative wording. It is why splitting a purchase into two instruments does not produce two separate assessments if the Commissioner takes the view that they were one arrangement. Section 33A(4) applies the provision to arrangements made before, on or after 7 December 2020, but not before 1 September 1999.

The exception in s 33A(5)

There is a statutory carve-out, and it is the whole of the defence. It is conjunctive, and both limbs have to be satisfied.

This is not a theoretical risk described in a circular. There is a published audit record with numbers attached, and it comes from parliamentary replies.

In its reply of 21 April 2023, the Ministry of Finance stated that s 33A empowers the Commissioner to disregard the individual steps and assess stamp duty as a single joint purchase. MOF described IRAS as using a risk-based approach, examining the facts and circumstances surrounding the specific case. No holding period is published and there is no safe harbour. The marker MOF gave was the transfer of the small share to a higher-ABSD-profile party within a very short period of time.

The Ministry of Finance told Parliament on 7 May 2024 that, as at April 2024, IRAS had completed the review of 187 such "99-to-1" cases, of which 166 cases were found to have involved tax avoidance, with approximately $60 million in ABSD and surcharges to be recovered. That is close to nine in ten among the cases selected for review, which tells you something about how the selection is done.

The surcharge sits on top. MOF states it is 50% of the additional duty payable. So the exposure is the ABSD that would have been assessed on a single joint purchase, less what was actually paid, plus half of that difference again. On a $2 million purchase where 60% should have applied to the whole rather than to 1%, that runs into seven figures before anyone has argued about late stamping penalties.

The agent is exposed too

In the same 21 April 2023 reply, MOF stated that IRAS refers property agents involved in these arrangements to the Council for Estate Agencies for investigation, with potential penalties including financial penalties and suspension of their registrations. An agent who proposes the structure is not a bystander to it.

And there is a criminal layer

Avoidance reassessed under s 33A is a civil matter. Lying to the auditor is not. IRAS has published the case of a mother and son who were the first to be convicted of giving false and misleading information to IRAS during a stamp duty audit. IRAS also states that evasion of duties is an offence under section 62 of the Stamp Duties Act.

Assume the transfer is clean — a real change in beneficial arrangement, nothing the Commissioner would look through. It still costs money, and the ABSD saving is one line in a stack of several. People routinely model the saving and not the stack.

The CPF line is the one that surprises people. CPF Board states that on transferring or selling a share of a property to someone else, the outgoing owner must refund the principal withdrawn with the accrued interest. That refund goes back into the CPF account, not the bank account, and on a long-held property the accrued interest can be a large fraction of the principal. One narrow exception: those aged 55 and above before 1 January 2013 who had already set aside their Full Retirement Sum by that date may not need to refund pre-2013 housing withdrawals.

A married couple who want to move rather than accumulate usually do not need to restructure anything. IRAS operates a remission that refunds the ABSD paid on the second property where the first is sold within a defined window. It carries none of the s 33A risk, because it is not an arrangement to reduce duty — it is the relief the legislature provided.

The cost of this route is cash flow, not duty. The ABSD is paid up front and refunded later, which means the money has to exist for the length of the window. That is a real constraint and it is why people reach for alternatives. It is still the first thing to price, because the alternative carries a contingent liability that does not expire on any published timetable.

There is a second category of genuine part-share transfer that is treated on its own terms: transfers arising from matrimonial proceedings. IRAS publishes dedicated remissions covering BSD, ABSD and SSD in that context. A transfer ordered or agreed on divorce is not the same animal as a transfer engineered to reset a property count, and IRAS treats it differently.

Decoupling an HDB flat is not a matter of cost or risk. It is not available. HDB defines resale of part-share as a change of flat ownership by way of a partial sale or purchase between family members at a mutually agreed price, and states that part-share resale is not permitted between married couples. That closes the route for the group most likely to want it.

• On divorce, HDB permits a buyer to purchase an ex-spouse’s share only if the divorce is finalised after the flat’s minimum occupation period has been met.
• After such a purchase, HDB requires the buyer to fulfil a fresh MOP before selling in the open market, renting out the flat, or investing in other property where at least one owner is a citizen.
• A change in ownership not through a sale is permitted on defined grounds only. HDB states the basis as a change in the existing family structure — divorce, marriage or the demise of an owner — or where the owners need an ownership change to retain the flat.
• Proposed owners must be immediate family members, at least 21, citizens or permanent residents, and must not already own an HDB flat, a DBSS flat or an executive condominium within its MOP.

The trust route is closed during MOP as well. HDB states that acquiring private residential property to hold on trust for another person, or being a beneficiary of a property held on trust, is also not allowed during the flat’s MOP.

This is not a decision anyone should take on the strength of an article, an agent’s spreadsheet, or a worked example on a website — including this one. Two things determine the outcome, and neither is arithmetic.

1. 01Whether the arrangement falls within s 33A(5). That is a legal characterisation of facts and intentions, applied by the Commissioner and reviewable on appeal. It is not something an agent is competent to certify, and it is not something a calculator can output.
2. 02Whether the documentary record supports that characterisation. The record is made contemporaneously, at the time of the purchase and the transfer, not reconstructed when a query letter arrives.

So instruct a conveyancing lawyer before any option is exercised, not after. Where the duty at stake is material — and on residential property here it usually is — the only view that settles the question is IRAS’s own, and IRAS accepts applications for assessment through myTax Portal. A written position obtained in advance costs a fraction of a surcharge assessed in arrears.

And where the goal is simply to move from one home to another, price the married-couple remission first. It carries a cash-flow cost and no contingent liability. That is a better problem to have.