IRAS caught 166 of 187. The 99-1 arrangement your friend recommended is the one being audited

If someone has told you that a 99-1 split is how smart buyers avoid ABSD, you need to know what happened to the people who did it. IRAS reviewed 187 of these arrangements. It found 166 of them to be tax avoidance. Around $60 million is being clawed back, and Section 33A lets IRAS add a 50% surcharge on top of the duty that should have been paid.

That is roughly nine in ten. Not a handful of aggressive outliers — the standard version of a structure that was being openly marketed by people who should have known better, and in some cases by people who did.

There is a lawful transaction that shares the name, and it is worth understanding the difference precisely. Two quite different things get called decoupling, and only one survives scrutiny.

What IRAS actually found

IRAS reviewed 187 cases of the 99-to-1 arrangement and identified 166 as involving tax avoidance. About $60 million in ABSD and surcharges is being clawed back. Section 33A of the Stamp Duties Act allows IRAS to disregard arrangements made to reduce duty, treat the separate purchases as a single joint purchase, and add a 50% surcharge to the duty recovered.

The two things called "decoupling"

1. Genuine decoupling

A couple already own a property jointly. One sells their share to the other at market value. Buyer’s Stamp Duty is paid on the transferred share, the outgoing owner is refunded their CPF with accrued interest, and the remaining owner refinances to carry the whole loan. The freed-up party can then buy a property as their first.

This is a real transfer with real consideration and real consequences. It is lawful. It is also expensive, and often less advantageous than it looks once BSD on the transferred share, legal fees and the CPF refund are counted.

2. The 99-to-1 arrangement

A buyer who can afford the property alone buys 99%, and adds a spouse or relative for 1%. Shortly after — sometimes within days — the 1% is transferred, or the structure is used so that the second party retains "first property" status for a later purchase. The 1% share has no commercial rationale beyond the duty saving.

That absence of commercial rationale is what Section 33A is written to catch.

Where the line sits

IRAS has not published a bright-line test, and anyone claiming a safe percentage or a safe waiting period is inventing it. What the cases point to is substance:

• Does the share held reflect what that person actually contributed and actually owns?
• Was there a purpose to the arrangement other than reducing duty?
• How long was the arrangement held before being unwound, and does that timeline make sense for any reason other than tax?
• Could the primary buyer have afforded the property alone — and if so, why was the co-owner added at all?

The arithmetic of genuine decoupling

Where decoupling is genuine, it still has to pay for itself. The costs are immediate and certain; the benefit is a future ABSD saving that depends on rates staying where they are.

• Buyer’s Stamp Duty on the transferred share, computed on its market value.
• The outgoing owner’s CPF principal and accrued interest, refunded to their CPF account rather than to cash.
• Legal fees for both the transfer and the refinancing, typically several thousand dollars.
• A fresh loan assessment on the remaining owner alone — who must now service the entire mortgage within their own TDSR.

That last point sinks more plans than the stamp duty does. One income carrying the whole loan, stress-tested at 4%, is a materially smaller borrowing capacity than two.