How to Calculate Remove GST (Reverse GST) in Singapore: A Step-by-Step Guide
Works backwards from a GST-inclusive price to show how much of it is GST.
Singapore's tax system is simple by global standards, but the progressive bands, reliefs and the 9% GST still trip people up. A quick calculation helps you set aside the right amount before IRAS sends your notice of assessment, or check that a bill has been worked out correctly.
What you need
- Price including GST (S$)
Step by step
- Enter the price including gst (S$).
- The results update as you type, or press Calculate.
- Read the gst included first, then the supporting figures below it.
The formula
GST portion = inclusive price × 9/109.
Worked example
For example, with these inputs:
- Price including GST (S$): 109
the calculator returns:
- GST included: S$9.00
- Price before GST: S$100.00
A second example
Now change the inputs to:
- Price including GST (S$): 136
the calculator returns:
- GST included: S$11.23
- Price before GST: S$124.77
Practical tips
- Set aside a little each month so the tax bill is not a shock, or sign up for GIRO instalments with IRAS.
- Personal income tax relief is capped at S$80,000 a year in total.
- Keep receipts and records for at least five years in case IRAS asks for them.
- SRS and CPF top-up relief save more tax the higher your marginal rate is.
Background
Singapore taxes individuals on income earned in Singapore, with progressive rates for residents that start at 0% on the first S$20,000 of chargeable income and rise to 24% on income above S$1 million. Tax is assessed a year in arrears: income earned in 2025 is assessed in Year of Assessment 2026.
IRAS issues a notice of assessment, usually from April onwards, and tax is due within a month, although most people opt for interest-free GIRO instalments. Estimating your bill early means you can budget for it instead of being surprised.
Tax planning in Singapore is mostly about timing and reliefs rather than complex structures. Topping up CPF, contributing to SRS and claiming every relief you qualify for can lower your marginal rate band, and the savings are larger for higher earners.
Related calculations
- Service Charge & GST Calculator: Restaurant bills in Singapore often show '++': a 10% service charge, then 9% GST on the subtotal.
- SRS Tax Savings Calculator: Shows how much tax you save by contributing to the Supplementary Retirement Scheme.
- CPF Cash Top-Up Tax Relief Calculator: Estimates the tax saved from Retirement Sum Topping-Up: up to S$8,000 for yourself and S$8,000 for family members.
- Rental (Lease) Stamp Duty Calculator: Calculates stamp duty on a tenancy agreement of four years or less at 0.4% of the total rent.
Want to skip the arithmetic? The free Remove GST Calculator (Reverse GST) does all of this instantly and updates as you type.
Run your own numbers: Remove GST Calculator (Reverse GST)