You will be able to identify other income that IRAS expects you to declare.
Log in to your income tax return and look at the income section. Every figure already there came from someone who reported it to IRAS. Your employer reports your salary, so IRAS pre-fills it. Nobody reports your side income, so it is missing from the pre-filled return. This is where many people go wrong: the return looks complete because the salary is filled in, but the side income is absent because IRAS never had it.
Darren teaches at a secondary school during the week. On Saturdays he gives two hours of maths tuition to two Secondary 3 students in Bishan, and in the school holidays he sometimes runs a short revision class. Last year he earned S$6,000 from this (an example figure), all paid by PayNow. He had never declared it, mainly because nobody asked and his return always looked complete when he logged in.
Side income is income from work you do for yourself outside your job, which nobody reports to IRAS. Because it usually comes from working for yourself, it counts as income from a trade, business, profession or vocation. You declare it in your return yourself, and it is taxable whether or not you think of it as a business. Any regular paid activity done for profit is taxable. Among people with a day job, the common ones are tutoring, freelance design or writing, photography, coaching, consulting, selling things you make, and paid speaking. Weekend photography counts, and so do designing a logo for a friend's cafe and commission earned referring clients to an agency.
Platform and app income is treated the same way as other side income. That covers delivery work, ride-hailing, renting out your car through an app, selling services on a freelance marketplace, and earning from a content channel. It is taxable even if the amounts are small and even if you did it for only a few months. There is no threshold below which side income stops counting.
A common wrong assumption is that a small amount need not be declared because it would not change the tax. If your chargeable income is in the zero band, it may not change the tax, but you must still declare it. Only the calculation shows whether the bill changes.
You declare net income, which is the income minus the expenses you incurred to earn it. Darren spent S$500 on printed worksheets and assessment books, so his net tuition income is S$6,000 - S$500 = S$5,500.
Before the tuition, Darren's chargeable income is S$33,000, taken from the practice table in Lesson 1.4, Rebuild your tax bill from scratch. His marginal rate at that level is 3%. Adding the tuition gives S$33,000 + S$5,500 = S$38,500, which is still inside the 3% band. His tax goes up by S$5,500 x 3% = S$165.
Darren read the IRAS guidance for people with income from a side job and confirmed the tuition was taxable. He added it to his return under trade income, with the expenses. He also started a simple spreadsheet recording the date, the student, the amount received, and any expense with its receipt. He then realised he had not declared the tuition in the previous two years either, and noted it as something to fix in module 7. Lesson 7.2, Mistakes, amendments and objections, explains what to do when you find an old year with income left out.
Selling your own used things is not income. It is disposing of personal belongings, and there is nothing to declare. If Darren sold his old bicycle and textbooks on Carousell, none of that would go on his return.
The line moves when you buy things in order to sell them for a profit, and do it repeatedly. That is a small trade, and the profit is taxable. Buying sneakers on release day and reselling them online every month is a trade. IRAS judges this with the same pattern it uses for investment gains: how often you do it, how organised it is, and why you bought the item. Lesson 5.1, Dividends, interest and investment gains, teaches that test in full.
Leaving side income out makes your return wrong. IRAS has ways to learn about undeclared income, and the penalties can be far larger than the tax itself.
If your side income grows, you take on more of the duties of a self-employed person. Your records need to support your expenses. If your net trade income passes a level set by the CPF Board, you become liable to pay MediSave contributions on it. The course Self-employed and freelance: money with irregular income covers these duties. Its module 4, File your income tax with records that hold up, deals with declaring trade income and allowable expenses in detail, and its module 2, Know your MediSave duty as a self-employed person, covers the MediSave side. For your return this year, you only need to make sure the side income goes on it.
To get your own return right:
Identify all income you earned outside your job, including platform and app income. Leave out sales of your own used belongings, and include any profit from repeatedly buying to resell. If you are unsure whether an item counts, check the IRAS guidance before leaving it out. Total the income and the expenses you incurred to earn it. Declare both in the return under trade income, so the figure taxed is income minus expenses. Keep records of the date, the client or student, the amount received, and each expense with its receipt. Note any past years where side income was left out, to fix using Lesson 7.2.
Now list every bit of income you earned outside your job last year and mark whether it was declared.
Write down any income you earned outside your job last year and note next to each whether you declared it.
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