Tax Saving Notebook

港台中产 · 2025-12-07

Joint Assessment or Separate Filing for Couples? Simulations to Find the Optimal Strategy

The 2025-26 Hong Kong Budget, delivered on 26 February 2025 by Financial Secretary Paul Chan, introduced a one-off reduction in salaries tax and tax under personal assessment of 100% of the tax payable for the year of assessment 2024-25, capped at HKD 3,000 per return. This cap is half the HKD 6,000 ceiling applied in the previous year. For married couples, this change directly alters the calculus of whether to file jointly under the joint assessment election (IRO s. 10(1A)) or separately as two individual taxpayers. The lower cap disproportionately benefits separate filings where each spouse receives their own HKD 3,000 reduction, compared to a single HKD 3,000 reduction for a joint return. With the standard tax rate at 15% for the 2024-25 year of assessment and the progressive rates banded from 2% to 17%, the optimal filing status is no longer a simple default for dual-income households. This article provides a structured simulation framework to determine the mathematically superior approach for Hong Kong tax-resident couples.

The Legislative Framework: Joint Assessment vs. Separate Taxation

The Inland Revenue Ordinance (Cap. 112) provides three distinct pathways for married couples: separate taxation for each spouse (the default), joint assessment under IRO s. 10, and personal assessment under IRO s. 41. The choice is irrevocable once the return is filed for that year of assessment.

The Default: Separate Taxation (IRO s. 5-8)

Under the territorial source principle, each spouse is taxed individually on their Hong Kong-sourced income. For salaries tax (IRO s. 8), this means each spouse computes their own assessable income, deducts their own personal allowances (e.g., basic allowance of HKD 132,000 for 2024-25), and applies the progressive tax rates (2% on the first HKD 50,000, rising to 17% on income over HKD 200,000). The alternative is a flat 15% on net chargeable income, whichever produces a lower liability. No election is required; this is the Inland Revenue Department’s (IRD) default treatment for married individuals.

The Election: Joint Assessment (IRO s. 10)

A married couple not living apart can elect for joint assessment under IRO s. 10(1A). This combines the total assessable income of both spouses into a single pool. The couple then receives a single married person’s allowance (HKD 264,000 for 2024-25) instead of two basic allowances (total HKD 264,000—identical in quantum). The key difference is the ability to offset one spouse’s losses against the other’s income and to utilise the progressive tax bands more efficiently when one spouse has significantly lower income.

The Alternative: Personal Assessment (IRO s. 41)

Personal assessment (IRO s. 41) aggregates all income—salaries, profits, and property—of each spouse separately, then applies a single set of allowances and progressive rates. For couples where one spouse has business losses, this can be beneficial, but it requires an election by 31 March of the year following the year of assessment.

Simulation 1: The Dual-Income Professional Couple

Consider a couple where Spouse A earns HKD 900,000 in salaries and Spouse B earns HKD 600,000. Both have no other income. For the 2024-25 year of assessment, the standard allowances and rates apply.

Separate Filing Calculation

Spouse A:

  • Assessable Income: HKD 900,000
  • Basic Allowance: HKD 132,000
  • Net Chargeable Income: HKD 768,000
  • Tax at progressive rates: First HKD 50,000 @ 2% = HKD 1,000; Next HKD 50,000 @ 6% = HKD 3,000; Next HKD 50,000 @ 10% = HKD 5,000; Next HKD 50,000 @ 14% = HKD 7,000; Remaining HKD 568,000 @ 17% = HKD 96,560. Total = HKD 112,560.
  • Tax at standard rate (15% of HKD 900,000): HKD 135,000.
  • Lower amount: HKD 112,560.
  • Less 2024-25 Budget reduction (capped at HKD 3,000): HKD 109,560.

Spouse B:

  • Assessable Income: HKD 600,000
  • Basic Allowance: HKD 132,000
  • Net Chargeable Income: HKD 468,000
  • Tax at progressive rates: First HKD 200,000 @ 2-14% = HKD 16,000; Remaining HKD 268,000 @ 17% = HKD 45,560. Total = HKD 61,560.
  • Tax at standard rate (15% of HKD 600,000): HKD 90,000.
  • Lower amount: HKD 61,560.
  • Less 2024-25 Budget reduction (capped at HKD 3,000): HKD 58,560.

Total Separate Tax Liability: HKD 109,560 + HKD 58,560 = HKD 168,120.

Joint Assessment Calculation

  • Combined Assessable Income: HKD 1,500,000
  • Married Person’s Allowance: HKD 264,000
  • Net Chargeable Income: HKD 1,236,000
  • Tax at progressive rates: First HKD 200,000 @ 2-14% = HKD 16,000; Remaining HKD 1,036,000 @ 17% = HKD 176,120. Total = HKD 192,120.
  • Tax at standard rate (15% of HKD 1,500,000): HKD 225,000.
  • Lower amount: HKD 192,120.
  • Less 2024-25 Budget reduction (capped at HKD 3,000): HKD 189,120.

Result: Separate filing saves HKD 21,000 (HKD 189,120 - HKD 168,120). The dual HKD 3,000 caps on separate filings (total HKD 6,000) versus a single HKD 3,000 cap on joint assessment contributes HKD 3,000 of this saving. The remainder comes from the progressive rate structure being applied more efficiently to two separate, lower net chargeable incomes.

Simulation 2: The Single-Income Household with a Dependent Spouse

Now consider Spouse A earning HKD 1,200,000 and Spouse B earning HKD 0. Spouse B has no income.

Separate Filing Calculation

Spouse A:

  • Assessable Income: HKD 1,200,000
  • Basic Allowance: HKD 132,000
  • Net Chargeable Income: HKD 1,068,000
  • Tax at progressive rates: HKD 16,000 (first HKD 200,000) + HKD 147,560 (remaining HKD 868,000 @ 17%) = HKD 163,560.
  • Tax at standard rate (15% of HKD 1,200,000): HKD 180,000.
  • Lower amount: HKD 163,560.
  • Less 2024-25 Budget reduction (capped at HKD 3,000): HKD 160,560.

Spouse B:

  • Assessable Income: HKD 0
  • No tax liability.
  • Budget reduction: HKD 0 (no tax payable).

Total Separate Tax Liability: HKD 160,560.

Joint Assessment Calculation

  • Combined Assessable Income: HKD 1,200,000
  • Married Person’s Allowance: HKD 264,000
  • Net Chargeable Income: HKD 936,000
  • Tax at progressive rates: HKD 16,000 (first HKD 200,000) + HKD 125,120 (remaining HKD 736,000 @ 17%) = HKD 141,120.
  • Tax at standard rate (15% of HKD 1,200,000): HKD 180,000.
  • Lower amount: HKD 141,120.
  • Less 2024-25 Budget reduction (capped at HKD 3,000): HKD 138,120.

Result: Joint assessment saves HKD 22,440 (HKD 160,560 - HKD 138,120). The married person’s allowance (HKD 264,000) is identical to two basic allowances (HKD 132,000 each), so the saving comes entirely from the progressive rate structure: a single net chargeable income of HKD 936,000 incurs less tax at the 17% marginal rate than a single net chargeable income of HKD 1,068,000, because the allowance is effectively doubled for the non-earning spouse.

Simulation 3: The Self-Employed Couple with Business Losses

Consider a couple where Spouse A has profits tax assessable profits of HKD 800,000 from a sole proprietorship, and Spouse B has a profits tax loss of HKD 200,000 from a separate sole proprietorship. Both have no salaries income.

Separate Filing Calculation

Spouse A:

  • Assessable Profits: HKD 800,000
  • Basic Allowance: HKD 132,000
  • Net Chargeable Income: HKD 668,000
  • Tax at progressive rates: HKD 16,000 (first HKD 200,000) + HKD 79,560 (remaining HKD 468,000 @ 17%) = HKD 95,560.
  • Tax at standard rate (15% of HKD 800,000): HKD 120,000.
  • Lower amount: HKD 95,560.
  • Less 2024-25 Budget reduction (capped at HKD 3,000): HKD 92,560.

Spouse B:

  • Assessable Profits: HKD 0 (loss of HKD 200,000, but under separate taxation, losses cannot be transferred to the other spouse).
  • No tax liability.
  • Budget reduction: HKD 0.

Total Separate Tax Liability: HKD 92,560.

Joint Assessment Calculation

  • Combined Assessable Profits: HKD 800,000 - HKD 200,000 = HKD 600,000
  • Married Person’s Allowance: HKD 264,000
  • Net Chargeable Income: HKD 336,000
  • Tax at progressive rates: First HKD 200,000 @ 2-14% = HKD 16,000; Remaining HKD 136,000 @ 17% = HKD 23,120. Total = HKD 39,120.
  • Tax at standard rate (15% of HKD 600,000): HKD 90,000.
  • Lower amount: HKD 39,120.
  • Less 2024-25 Budget reduction (capped at HKD 3,000): HKD 36,120.

Result: Joint assessment saves HKD 56,440 (HKD 92,560 - HKD 36,120). The loss offset is the primary driver. Under IRO s. 19C, a sole proprietor’s loss can only be carried forward against his own future profits unless joint assessment is elected, which permits the loss to be set against the spouse’s income in the same year.

Decision Matrix: When to Elect Joint Assessment

The simulations reveal a clear pattern. Joint assessment is mathematically superior when:

  • One spouse has significantly lower income than the other (single-income households), as the married person’s allowance effectively doubles the tax-free threshold for the higher earner.
  • One spouse has business or property losses, as joint assessment allows immediate offset against the other spouse’s income.
  • The combined net chargeable income after allowances is low enough that the progressive rate bands are not fully exhausted by one spouse alone.

Separate filing is superior when:

  • Both spouses have substantial, similar incomes, as the separate progressive rate bands and the dual Budget reduction caps produce a lower aggregate liability.
  • One spouse has tax credits or deductions that are non-transferable (e.g., home loan interest under IRO s. 26E, which is capped at HKD 100,000 per taxpayer per year of assessment—joint assessment limits this to a single cap).

The IRD’s official guide, “Salaries Tax and Personal Assessment – A Guide for Married Persons” (I.R.D. No. 61), published in August 2024, confirms that the election must be made in writing on the tax return and cannot be revoked after the assessment is finalised.

The 2025-26 Budget Impact: A Structural Shift

The 2025-26 Budget reduction of HKD 3,000 per return is not merely a one-off concession; it creates a structural advantage for separate filing that persists as long as the cap is lower than the previous year’s. For the 2024-25 year of assessment, the HKD 3,000 cap represents a 50% reduction from the HKD 6,000 cap for 2023-24. For a couple with two moderate incomes, this alone can tip the balance.

Consider a marginal case: Spouse A earns HKD 300,000, Spouse B earns HKD 300,000. Under separate filing, each pays approximately HKD 3,360 in tax (after allowances and progressive rates), totalling HKD 6,720. After the HKD 3,000 cap per return, each pays HKD 360, totalling HKD 720. Under joint assessment, the combined tax is HKD 6,720, reduced by HKD 3,000 to HKD 3,720. Separate filing saves HKD 3,000 purely from the dual caps.

The Financial Secretary’s Budget Speech (Hansard, 26 February 2025) explicitly stated the reduction is “to ease the burden on taxpayers amid global economic uncertainties.” For dual-income couples, the policy achieves this by rewarding separate filings.

Actionable Takeaways

  1. For the 2024-25 year of assessment, run a side-by-side computation for both joint assessment and separate filing, as the dual HKD 3,000 Budget reduction caps create a minimum HKD 3,000 advantage for separate filing in most dual-income scenarios.
  2. Elect joint assessment only if one spouse has business losses or if the income disparity is so large that the progressive rate savings exceed the loss of the second Budget reduction cap.
  3. Claim all non-transferable deductions (home loan interest, charitable donations up to 35% of assessable income) on the higher-earning spouse’s return under separate filing to maximise their utilisation.
  4. Document the election in writing on the tax return (BIR60) by the filing deadline of 2 June 2025 for the 2024-25 year of assessment, and retain a copy of the computation.
  5. Review the election annually, as changes in income levels, Budget measures, or the birth of a child (which introduces a child allowance of HKD 130,000 per child for 2024-25) can shift the optimal filing status.

Disclaimer: 本文不構成稅務建議。涉及個人稅務情況請諮詢持牌會計師或稅務師。This does not constitute tax advice. Consult a licensed CPA or tax advisor for your specific situation.