GST on Aircon Work in Singapore: How to Read a Quote

Singapore ties GST registration to size, not standing: the First Schedule to the Goods and Services Tax Act makes a business liable once taxable supplies in a calendar year pass one million dollars. The duty arrives earlier if there are reasonable grounds to believe the figure will be passed in the next twelve months, and both tests measure sales volume rather than the quality of work sold. Below that line registration becomes a choice, since the Act lets a business that is not liable ask to be registered anyway, with the decision resting on the Comptroller. So two honest operators can produce two different quotes: one below the threshold quoting with no tax, one above it quoting with the tax inside the number.

The tax also cannot be charged by just anyone. The Act makes it an offence to collect, or attempt to collect, an amount as tax where the collector has no entitlement to do so, with a penalty running to several times the sum collected. A small firm quoting with no tax line is following that rule, and reading the absence as evasion gets the arrangement backwards.

None of this makes a GST line a mark of quality either. Crossing the threshold means a business sold more in a calendar year, which usually means more vans, more technicians or more years in operation. Those track scale, not diagnostic skill, so a homeowner who picks on the tax line alone has swapped one poor proxy for another.

The rate has been 9% since 1 January 2024. Section 16 of the Act carries the ladder behind it: 4% in 2003, 5% from 2004, then 7% for most of the two decades that followed, with an 8% year through 2023. Older material still quoting 7% or 8% is the usual reason two sources appear to disagree, so check the date on anything that states a rate.

Parts and labour sit at the same rate. Section 16 charges goods and services at one figure, so an invoice split into a compressor line and a labour line is treated no differently from one showing a single total. A supply-and-install job is charged the same way as a visit that fits nothing, and the split on the page changes nothing about the tax.

Aircon work also falls outside the exempt categories, which are narrow: financial services, the sale and lease of residential property, and investment precious metals. Servicing, repairing or installing a unit is a supply of services made in Singapore, so it sits in the ordinary standard-rated group, and an HDB flat, a condo unit and a shop are treated alike.

Rounding explains the last dollar or two, and nothing more. IRAS allows the tax line to be worked out line by line and added up, or once on the total before tax, as long as one method is used consistently. Two quotes covering identical work can therefore land a few cents apart with neither being wrong.

A registered business is meant to quote the tax-inclusive figure already. IRAS puts the rule plainly in its general guide: prices displayed, advertised, published or quoted to the public must show the price with the tax in it. The guide treats a bare number followed by plus GST as a failed display format, and requires the inclusive figure to be at least as prominent as the exclusive one when both appear. Breaching the display rule carries a fine, but a wrongly built quote is worth one clarifying question and no more; it is a formatting problem, not a character reference.

The failure mode is a comparison run across two different bases. An inclusive quote and an exclusive quote for identical work look 9% apart when the work behind them is the same, and the whole gap is an artefact of how the two pages were written. Put both onto one basis before anything else: multiply an exclusive figure by 1.09, or take 9 over 109 out of an inclusive figure to recover the number before tax.

A number given over the phone deserves the same treatment, because the display rule covers spoken quotations. Getting the same number in writing is still the safer habit, since a spoken figure is the one nobody can check afterwards and each side tends to remember it on a different basis. That is how an argument about scope becomes an argument about arithmetic.

A homeowner rarely receives a tax invoice, and that is the system working as designed: the tax invoice exists so a GST-registered customer can support an input tax claim, which makes it a business-to-business document. IRAS says it need not be issued to a customer who is not registered, so a registered operator may issue a receipt instead, and the receipt is where the tell sits.

The receipt has a set shape. IRAS requires it to show the business name and GST registration number, the date, the total payable including tax, and a line saying that the price payable includes GST. Those last two items are the tell, and a homeowner who knows to look for them needs to ask nobody anything.

A business that is not registered must not issue a tax invoice at all. The same IRAS guide lists that among the cases where a tax invoice is barred. That is why paperwork from a smaller operator can look thin. An ordinary invoice with no tax line is the right output below the threshold, so asking for a tax invoice asks for a document the business cannot lawfully give.

The number on a receipt can be checked against the register. IRAS runs a GST Registered Business Search as a public service, and a number either matches a registered business or it does not. Use it to settle a quote that reads ambiguously, rather than running it on everyone who walks into the flat.

One question closes the gap: is this figure inclusive of GST. Put it in writing and keep the reply next to the quote. A registered business should confirm the total already carries the tax, and a business below the threshold should confirm none applies; either reply is a complete answer.

Two replies deserve a closer read. Absorbing the tax and having no tax to charge are different claims. IRAS treats the second as misleading where a registered business is in fact discounting by the tax amount, since a tax element still sits inside everything such a business supplies. An absorbed tax is a discount under another name, and discounts get withdrawn.

None of this is a verdict on who to hire. The basis a quote was written on tells you how to read the number in front of you, but it cannot tell you whether the diagnosis behind the number holds up. A quote settled on tax and wrong on scope still ends with the wrong work done, with every page correctly taxed.

So treat the tax question as the quick one: confirm the basis in a message and put the competing quotes onto that same basis. Then turn to what each one claims was found and what it proposes to do. Sending a quote alongside a description of the symptom lets both halves be read together.