You will be able to identify other income that IRAS expects you to declare.
Darren teaches at a secondary school during the week. On Saturdays he gives two hours of maths tuition to a pair of Secondary 3 students in Bishan, and in the school holidays he sometimes runs a short revision class. Last year that came to S$6,000, an example figure, all paid by PayNow. He had never declared it, mostly because nobody had ever asked, and his return had always looked complete when he logged in.
That is the trap with side income. The return looks finished because IRAS has filled in your salary. The side income is missing because IRAS never had it. This lesson covers what counts and what to do about it.
Your employer reports your salary. Nobody reports your tuition fees, your weekend photography, the logo you designed for a friend's cafe, or the commission you earned referring clients to an agency. Income like this usually comes from work you do for yourself, so it counts as income from a trade, business, profession or vocation, and you declare it in your return yourself.
That is true whether you think of it as a business or not. A regular paid activity done for profit is taxable. Tutoring, freelance design or writing, photography, coaching, consulting, selling things you make, and paid speaking are all common examples among people with a day job.
What you declare is the net figure: the income minus the expenses you incurred to earn it. Darren's expenses were small, S$500 in this example, for printed worksheets and assessment books. So he would declare S$6,000 of income and S$500 of expenses, giving S$5,500 of net income.
Income earned through apps and platforms is treated the same way. Delivery work, ride-hailing, renting out your car through an app, selling services on a freelance marketplace, or earning from a content channel are all taxable, even if the amounts are small and even if you only did it for a few months.
There is no threshold below which side income stops counting. Some people assume a small amount doesn't need declaring because it wouldn't change their tax. It may well not change it, if your chargeable income is in the zero band. But it should still be declared, and only the calculation will tell you whether it changes the bill.
Selling your own used things isn't income. If Darren sells his old bicycle and a pile of textbooks on Carousell, that's disposing of personal belongings, and there's nothing to declare.
The line moves once you buy things in order to sell them for a profit, repeatedly. Someone who buys sneakers on release day and resells them online every month is running a small trade, and the profit is taxable. The test is the same pattern IRAS uses for investment gains in lesson 5.1, Dividends, interest and investment gains: how often, how organised, and why you bought.
Under the practice table from lesson 1.4, Rebuild your tax bill from scratch, Darren's chargeable income was S$33,000, at a marginal rate of 3%. Adding S$5,500 of net tuition income takes him to S$38,500, still inside the 3% band, so his tax would rise by S$165.
That is not a large amount. Leaving it out, though, makes his return wrong, and IRAS has ways to learn about income that wasn't declared. Penalties for undeclared income can be far larger than the tax itself. Lesson 7.2, Mistakes, amendments and objections, covers what to do if you find an old year with income left out.
If your side income grows, you start taking on more of the duties of a self-employed person. Your records need to support your expenses. And if your net trade income passes a level set by the CPF Board, you become liable to pay MediSave contributions on it.
All of that is taught in Self-employed and freelance: money with irregular income. Its module 4, File your income tax with records that hold up, covers 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. This lesson only makes sure you know the income has to go on your return.
Darren read the IRAS guidance for people with income from a side job, and confirmed that the tuition was taxable. He added it to his return under trade income, with the expenses, and started a simple spreadsheet: date, student, amount received, and any expense with its receipt. He also realised he hadn't declared the tuition in the previous two years, and wrote that down as something to fix in module 7.
When you're unsure whether an item counts, check the IRAS guidance before leaving it out. For the activity, list every bit of income you earned outside your job last year and mark whether it was declared.
List any income outside your job from last year and write whether it was declared.
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