To declare side income for tax in Singapore, report it to IRAS as trade or business income in your annual tax return, not as salary. If your side gig makes money from work you do yourself, it counts as taxable self-employed income and goes under "trade, business, profession or vocation" in Form B or B1 during tax season each year.
Plenty of students, NSFs, and fresh grads earn on the side now: freelance design, tuition, dropshipping, content, reselling, food stalls at pop-ups. That money is not automatically tax-free just because it is small or paid to your personal bank account. The rules are clear once you see them, and getting this right early saves you a nasty letter from IRAS later.
Is your side income taxable?
Most side income earned in Singapore is taxable. IRAS treats profit from any trade, business, profession, or vocation as taxable income, whether you do it full time or a few hours a week. The IRAS self-employed and partnerships guide (as of June 2026) is the primary reference for how this works.
There is a line between a hobby and a trade. If you sell an old phone or a few used items now and then, that is usually not a trade. If you buy or make things regularly to sell for profit, run tuition classes, take freelance clients, or drive for a platform, you are carrying on a trade and the profit is taxable. Money from a one-off gift or a personal sale is different from money you set out to earn repeatedly.
Being taxable does not always mean you owe tax. Singapore's personal income tax is progressive, and the first chunk of chargeable income is taxed at zero. Even so, you still have to declare the income. Declaring it and paying zero is fine. Not declaring it is the problem.
Trade income versus employment income
Side income splits into two very different buckets, and mixing them up is the most common mistake.
Employment income is what you get as an employee: a monthly salary, part-time wages with CPF, a paid internship where the company controls your hours and work. Your employer usually reports this to IRAS through the Auto-Inclusion Scheme, so it can appear in your tax return already filled in. You report it under employment.
Trade or business income is what you earn working for yourself: freelance invoices, tuition fees paid to you directly, sales from your online shop, commissions, gig platform payouts. Nobody reports this for you. You declare it yourself as self-employed income, and you can deduct the costs of earning it. The test is control and independence. If you decide how and when the work gets done and you carry the risk, it is trade income.
The 2-line and 4-line statement
When you declare trade income, IRAS asks for a simple summary of your business figures, not a full set of company accounts. How much you report depends on your revenue for the year, per the IRAS guide on calculating business income (as of June 2026).
If your revenue is $200,000 or less for the year, you submit a 2-line statement: your revenue and your adjusted profit or loss. That is it. Most side hustlers fall here.
If your revenue is more than $200,000, you submit a 4-line statement: revenue, gross profit or loss, allowable business expenses, and adjusted profit or loss. Revenue means your total takings before expenses. Adjusted profit is what is left after you subtract allowable expenses, and that profit is the figure that gets taxed.
Revenue is not the same as profit. If you sold $8,000 of handmade goods and spent $3,000 on materials and delivery, your revenue is $8,000 but your adjusted profit is closer to $5,000. You are taxed on the profit, so tracking both numbers matters.
Allowable and disallowable expenses
You can subtract the costs of running your side business, which lowers the profit you get taxed on. The rule is that an expense must be incurred wholly and exclusively to earn that income, and it must be revenue in nature, not a private or capital cost. The IRAS page on business expenses and deductions (as of June 2026) lists what qualifies.
Allowable expenses for a typical side hustle can include platform fees, payment processing charges, advertising, materials and stock, delivery and postage, and the portion of your phone or internet used for the business. Disallowable costs include your own drawings, private meals, personal clothing, fines, and the cost of buying long-term equipment like a laptop as a lump sum (that is capital, though capital allowances may apply). Do not deduct personal spending dressed up as business spending. If IRAS reviews you and the claim does not hold, you pay the tax plus a penalty.
Records you need to keep
You must keep proper records of your income and expenses for at least five years, even if you only file a 2-line statement. IRAS can ask to see them, and the IRAS record-keeping guide (as of June 2026) sets the five-year rule. Start a simple spreadsheet from your first sale rather than reconstructing a year of chaos in April.
Here is what to track as you go.
| What to track | Why it matters | Keep for |
|---|---|---|
| Every sale or invoice (date, amount, client) | Adds up to your revenue figure | 5 years |
| Receipts for materials and stock | Deductible cost of goods sold | 5 years |
| Platform and payment fees | Allowable expense, often overlooked | 5 years |
| Advertising and marketing spend | Allowable expense | 5 years |
| Transport and delivery costs | Allowable if business-related | 5 years |
| Bank and payout statements | Proof of what you actually received | 5 years |
| Business-use share of phone/internet | Partial deduction, needs a basis | 5 years |
Keep a separate bank account or wallet for the side business if you can. It makes the numbers obvious and the record-keeping painless.
When you must register for GST or a business name
Two thresholds catch people by surprise, though most side hustlers never hit them.
GST registration becomes compulsory when your taxable turnover exceeds $1 million, based on the IRAS GST registration guide (as of June 2026). You must register if your turnover crossed $1 million over the past calendar year, or if you reasonably expect it to cross $1 million in the next 12 months. Below that, GST is optional and usually not worth the admin for a small operation.
Separately, if you trade under a business name rather than your own full name, you generally register the business with ACRA. Sole proprietorships and partnerships are set up through ACRA's BizFile portal, and the ACRA how-to guides walk through it. Registering with ACRA and declaring income to IRAS are two separate steps. Doing one does not cover the other.
Deadlines, MediSave, and penalties
Tax season runs from 1 March, and e-Filing closes on 18 April each year (IRAS, as of June 2026). File through the myTax Portal with your Singpass. If you had any trade income during the year, you file Form B; if you only had employment income, it is Form B1. IRAS then sends a Notice of Assessment with the tax payable.
If you are self-employed and your net trade income for the year is more than $6,000, you also owe MediSave contributions to CPF, based on the CPF self-employed MediSave guide (as of June 2026). This is separate from income tax and is calculated on your declared net trade income, which is one more reason to declare accurately.
Filing late or under-declaring income leads to penalties, and IRAS does cross-check bank and platform data. Coming forward and correcting an honest mistake is treated far better than being caught. If you have earned side income and never declared it, fix it in your next filing rather than hoping it stays hidden.
If this is your first time filing at all, read our walkthrough on how to file income tax for the first time in Singapore, and if you are still building the income itself, our guide on how to start a side hustle as a student in Singapore covers the earning side. Both pair well with getting the tax right.
Common questions about declaring side income
Do I need to declare side income if it is only a few hundred dollars?
Yes, if it comes from a trade or activity you do to earn money repeatedly. There is no minimum "too small to declare" amount for trade income. You may end up paying zero tax because of the tax-free band, but you still declare the income. The only common exception is a genuine one-off personal sale, which is not a trade.
How do I report freelance or tuition income to IRAS?
You declare it as self-employed trade income in Form B during tax season, using a 2-line statement if your revenue is $200,000 or less. Enter your revenue and your adjusted profit after allowable expenses. Keep every invoice and receipt for at least five years in case IRAS asks to verify the figures.
What happens if I never declared my side income before?
Declare it in your next filing and, if you missed past years, use IRAS's process for reporting previously unreported income. Voluntary disclosure of an honest mistake usually carries a lighter penalty than an amount IRAS uncovers on its own. Paying the tax you owe now is cheaper than the fines that come with being investigated.
Getting money in is one skill. Keeping it clean with IRAS is another, and it is the boring part that protects everything you build. FINternship's mentors have guided over 1,000 young Singaporeans through exactly these early money decisions. You can apply to the free apprenticeship or start with our free masterclass to learn the money and career basics school never taught you.