7 Common IRAS Tax Filing Mistakes and How to Avoid Them

Filing personal income taxes with the Inland Revenue Authority of Singapore (IRAS) is generally a seamless experience due to user-friendly digital portals and high rates of automated employer filing. However, tax compliance remains a personal legal responsibility. Even minor oversights can lead to audits, tax re-assessments, and monetary penalties.

As you prepare for the Year of Assessment (YA) 2026 filing season, it is vital to review your declarations carefully. Here, we outline the 7 most common tax filing mistakes made by taxpayers in Singapore and provide clear guidance on how to avoid them.

1. Confusing Year of Assessment (YA) and Calendar Year

In Singapore, income tax is assessed on a preceding-year basis.

• Calendar Year: The period in which you earn your income (1 January to 31 December).
• Year of Assessment (YA): The year in which IRAS assesses and taxes the income earned in the preceding calendar year.

*The Mistake*: Declaring income earned in 2026 during the YA 2026 filing cycle.

*How to Avoid*: For YA 2026, you must declare income earned from 1 January 2025 to 31 December 2025. Any income earned in 2026 should only be declared in YA 2027.

2. Exceeding the SGD 80,000 Personal Income Tax Relief Cap

To maintain progressivity, Singapore imposes a hard cap of SGD 80,000 on the total amount of personal income tax reliefs a taxpayer can claim in a single Year of Assessment.

*The Mistake*: Topping up CPF accounts or the SRS assuming it will further reduce tax liability, without realizing that existing reliefs (such as compulsory employee CPF contributions, which will increase due to the OW ceiling adjustment to SGD 8,000 in 2026) have already pushed them past the SGD 80,000 threshold.

*How to Avoid*: Calculate your mandatory reliefs (like employee CPF and Earned Income Relief) before making voluntary cash contributions. Any amount contributed beyond the SGD 80,000 limit will not yield tax relief.

3. Wrongly Claiming Spouse Relief

Taxpayers can claim Spouse Relief (currently SGD 2,000, or SGD 5,500 if the spouse is handicapped) if they have supported their spouse.

*The Mistake*: Claiming Spouse Relief when the spouse's annual income exceeds the statutory threshold.

*How to Avoid*: For YA 2026, your spouse’s annual income in the preceding year must not have exceeded SGD 8,000 (raised from SGD 4,000 in previous YAs). If your spouse earns more than SGD 8,000, you are ineligible to claim this relief.

4. Double-Claiming Child Reliefs

Parents can claim Qualifying Child Relief (QCR) or Handicapped Child Relief (HCR) to ease the cost of raising children.

*The Mistake*: Both parents claiming 100% of the child relief for the same child, or claiming shares that aggregate to more than 100% (e.g., each parent claims SGD 4,000 QCR for the same child, totaling SGD 8,000 instead of the maximum SGD 4,000 allowed per child).

*How to Avoid*: Discuss and agree with your spouse on the apportionment before filing. You can split the QCR in any proportion (e.g., 50/50, 70/30, or 100/0), but the total claim across both parents must not exceed SGD 4,000 per child (or SGD 7,500 for HCR).

5. Assuming the Auto-Inclusion Scheme (AIS) Covers Everything

Many employers participate in the Auto-Inclusion Scheme (AIS) for Employment Income, meaning they submit salary details directly to IRAS.

*The Mistake*: Assuming that because your employer is in the AIS, you do not need to file a return or review your tax portal.

*How to Avoid*: Even if you receive a "No-Filing Service" (NFS) notification, you are legally required to log in to myTax Portal to verify that the pre-filled information is correct. Furthermore, you must manually declare any other taxable income (such as rental income or freelance commissions) and verify that all eligible reliefs are claimed.

6. Failure to Declare Rental Income and Claiming Wrong Deductions

Rental income is fully taxable in Singapore.

*The Mistake*: Failing to declare gross rental income, or claiming capital expenses (such as the first tenancy agent commission or renovation costs) as deductible expenses.

*How to Avoid*: Declare your gross rent and choose either the Simplified Expense Claim (15% flat rate of gross rent + mortgage interest) or keep all receipts to claim actual allowable expenses (such as repairs and subsequent agent fees).

7. Not Declaring ESOP and Share Plan Gains

Gains from Employee Share Options (ESOP) and Employee Share Ownership (ESOW) plans are treated as taxable employment income, not tax-free capital gains.

*The Mistake*: Forgetting to declare equity gains when exercising options or when shares vest, particularly if the employer does not participate in the AIS.

*How to Avoid*: Keep records of exercise dates and vesting dates. Calculate the difference between the open market value and the price paid, and declare this gain under "Other Employment Income" if your employer has not auto-included it.

By avoiding these 7 common errors, you can ensure a smooth, audit-free tax season in Singapore while preserving your hard-earned cash.