Hong Kong Mortgage Interest for US Expats: Does Foreign Mortgage Interest Qualify for Deduction?

For the US citizen or Green Card holder living in Hong Kong, the question of whether mortgage interest paid on a Hong Kong property can be deducted on a US federal tax return is a perennial source of confusion. The short answer is that it can, but only under specific and often restrictive conditions. The 2025 tax filing season, with its heightened IRS scrutiny on foreign assets and deductions claimed via Schedule A (Itemized Deductions), makes this a particularly relevant issue. While the Tax Cuts and Jobs Act (TCJA) eliminated the deduction for home equity loan interest not used to buy, build, or substantially improve the home, the core rules for acquisition indebtedness remain intact. For the Hong Kong-based US expat, the key is distinguishing between a primary residence and a second home, and then navigating the intersection of the US mortgage interest deduction rules with the Hong Kong territorial source principle, which governs local taxation but has no bearing on US federal deductions. The IRS does not care where the mortgage is located; it cares whether the debt is “acquisition indebtedness” as defined under IRC § 163(h)(3).

The Core Statutory Framework: IRC § 163(h)(3) and Acquisition Indebtedness

The deductibility of mortgage interest for US taxpayers is governed by IRC § 163(h)(3). This section allows a deduction for interest paid on “acquisition indebtedness” with respect to a “qualified residence.” The term “qualified residence” includes a taxpayer’s principal residence and one other residence (a second home). For a US expat living in Hong Kong, their Hong Kong apartment can qualify as either their principal residence or their second home, provided they meet the ownership and use tests.

Defining Acquisition Indebtedness

Acquisition indebtedness is debt incurred in acquiring, constructing, or substantially improving a qualified residence. The debt must be secured by that residence. Under IRC § 163(h)(3)(B)(i), the total amount of debt treated as acquisition indebtedness for any period cannot exceed USD 750,000 (USD 375,000 for married filing separately). This cap applies to the combined total of acquisition indebtedness for the principal residence and the second home. For debt incurred before December 16, 2017, the limit is USD 1,000,000 (USD 500,000 for MFS), as per the TCJA transition rules.

The Qualified Residence Test for Hong Kong Property

To deduct interest on a Hong Kong mortgage, the property must meet the definition of a “qualified residence.” IRC § 163(h)(4)(A)(i) defines a principal residence by reference to IRC § 121, which generally requires the taxpayer to have lived in the home for at least two of the five years preceding the sale. For a second home, the taxpayer must use the home for personal purposes for the greater of 14 days or 10% of the number of days it is rented out during the year (IRC § 280A(d)(1)). A Hong Kong property used solely as a rental property, where the taxpayer does not use it for personal purposes, does not qualify. The mortgage interest on such a property is generally treated as a rental expense, deductible on Schedule E, subject to the passive activity loss rules of IRC § 469.

Hong Kong Mortgage Structures and US Tax Treatment

The mechanics of a Hong Kong mortgage—typically denominated in HKD and often with an interest-only period or a floating rate tied to HIBOR—do not inherently disqualify the interest from deduction. The IRS treats foreign-currency debt as a liability, and the interest is deductible in USD at the spot rate on the date of payment or the average exchange rate for the year, depending on the taxpayer’s accounting method.

Interest-Only Periods and HIBOR-Linked Loans

Many Hong Kong mortgages offer an initial interest-only period, followed by a principal-and-interest repayment schedule. For US tax purposes, the deductibility of interest during the interest-only period is not affected by the absence of principal repayment. The debt remains acquisition indebtedness as long as the loan proceeds were used to acquire, construct, or substantially improve the qualified residence. The floating rate tied to HIBOR (Hong Kong Interbank Offered Rate) is a standard commercial rate. The IRS does not distinguish between fixed and variable rates for the purpose of the mortgage interest deduction, provided the loan is secured by the qualified residence.

Points and Prepayment Penalties

If the taxpayer paid points to secure a lower interest rate on the Hong Kong mortgage, those points are generally deductible as mortgage interest over the life of the loan, not in the year paid. Under IRC § 461(g)(2), points paid on the purchase or improvement of a principal residence can be deducted in the year paid, but this rule applies only to principal residences. For a second home, points must be amortized over the loan term. Prepayment penalties, if incurred, are generally deductible as interest, as they are considered additional charges for the use of borrowed money.

Interaction with the Foreign Tax Credit and the Hong Kong Territorial System

A common misconception is that because Hong Kong does not tax mortgage interest (or, more accurately, does not allow a deduction for it under the territorial source principle), the US deduction is somehow nullified. This is incorrect. The US mortgage interest deduction is a separate benefit under US law, independent of the Hong Kong tax treatment.

The Hong Kong Territorial Source Principle

Hong Kong taxes only income sourced in Hong Kong. Mortgage interest paid on a Hong Kong property is not itself a taxable event. However, for a Hong Kong taxpayer who rents out the property, the rental income is subject to Hong Kong Property Tax at a standard rate of 15% (for the 2024/25 year of assessment). The Inland Revenue Ordinance (Cap. 112) does not allow a deduction for mortgage interest against property tax. This is a key difference from the US system. The US expat cannot double-dip: the mortgage interest is either a Schedule A itemized deduction for a qualified residence or a Schedule E rental expense, but it cannot be deducted in both jurisdictions.

The Foreign Tax Credit (FTC) and Its Limits

If the Hong Kong property is rented out, the taxpayer may be able to claim a foreign tax credit for the Hong Kong Property Tax paid against their US tax liability on the same rental income. However, IRC § 904 limits the FTC to the proportion of US tax attributable to foreign-source income. The FTC is computed on Form 1116. The mortgage interest, if deducted as a rental expense on Schedule E, reduces the net rental income and, consequently, the amount of foreign tax credit that can be claimed. The taxpayer must carefully weigh whether it is more beneficial to treat the property as a qualified residence (deducting interest on Schedule A) or as a rental property (deducting interest on Schedule E and claiming an FTC). This decision hinges on the amount of other itemized deductions, the taxpayer’s overall US tax bracket, and the amount of Hong Kong Property Tax paid.

Practical Filing Considerations: Forms, Thresholds, and Statute of Limitations

The US expat must be meticulous in reporting the mortgage interest deduction. The IRS does not accept a simple statement of “Hong Kong mortgage interest.” The deduction must be substantiated.

Schedule A (Itemized Deductions) and Form 1098 Substitute

For a qualified residence, the deduction is reported on Schedule A, Line 8 (Home Mortgage Interest). If the mortgage is held by a foreign lender (which is almost always the case for a Hong Kong mortgage), the taxpayer will not receive a Form 1098. The IRS requires the taxpayer to attach a statement to the return, providing the name and address of the lender, the amount of interest paid, and the amount of the outstanding principal. This is a substitute for Form 1098. The taxpayer must also complete the “Home Mortgage Interest” worksheet in the Schedule A instructions to calculate the deductible interest, ensuring the total acquisition indebtedness does not exceed the USD 750,000 cap.

FBAR, FATCA, and the Mortgage Liability

The mortgage itself, as a liability, is not reportable on the FBAR (FinCEN Form 114) or FATCA Form 8938. However, the bank account from which the mortgage payments are made is reportable. If the taxpayer has a Hong Kong bank account used to pay the mortgage, and the aggregate value of all foreign financial accounts exceeds USD 10,000 at any time during the calendar year, an FBAR must be filed. Similarly, if the value of specified foreign financial assets exceeds the applicable threshold (USD 200,000 for a taxpayer living abroad, or USD 400,000 for married filing jointly), Form 8938 must be filed. Failure to file these forms can result in significant penalties, even if the mortgage interest deduction is properly claimed.

Statute of Limitations and IRS Examination Cycles

The general statute of limitations for an IRS assessment is three years from the filing date (or the due date, whichever is later), as per IRC § 6501(a). However, if the taxpayer fails to report more than USD 5,000 of gross income from a foreign financial asset, the statute is extended to six years (IRC § 6501(e)(1)(A)). The IRS is currently running a campaign targeting high-income taxpayers with foreign assets, including mortgages on foreign properties. The IRS Large Business & International (LB&I) division has issued practice units on the foreign mortgage interest deduction. Taxpayers should maintain all records—loan agreements, interest statements from the Hong Kong lender, proof of payment, and evidence of the use of loan proceeds—for at least six years after the return is filed.

Actionable Takeaways

1. A Hong Kong mortgage on a property used as the taxpayer’s principal residence or a qualifying second home can generate a deductible expense on US Schedule A, subject to the USD 750,000 acquisition indebtedness cap under IRC § 163(h)(3).
2. The foreign status of the lender and the HKD denomination of the loan do not affect deductibility, but the taxpayer must maintain a substitute for Form 1098, including the lender’s name and the interest paid, to attach to the return.
3. Hong Kong Property Tax paid on rental income from the same property may be eligible for a foreign tax credit on Form 1116, but deducting the mortgage interest as a rental expense on Schedule E will reduce the net rental income and the corresponding FTC.
4. The bank account used to pay the mortgage is a reportable foreign financial account for FBAR and FATCA purposes; failure to file these reports can trigger penalties separate from any mortgage interest deduction issue.
5. The IRS examination cycle for foreign mortgage interest deductions is active, and the statute of limitations on assessment can extend to six years if the taxpayer has significant unreported foreign financial assets.

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.