What Congress actually dropped
The Senate Finance Committee's July 28 Chairman's Mark included a narrow relief package, but the substantive foreign-currency provisions did not make it in. A discussion draft had proposed letting taxpayers deduct foreign currency losses tied to a mortgage on a residence abroad, and losses on the sale of that residence, against gain recognized. It also proposed raising the personal transaction exemption under Section 988(e) from $200 to $1,000, indexed for inflation. None of that survived. For more on what the same markup did—and didn't do—see our breakdown of the Senate Finance Committee's FBAR reform bill.
Why a Swiss mortgage can create a phantom gain
A US person who borrows Swiss francs to buy a principal residence is holding two separate tax instruments. The home is one; the franc-denominated debt is another. Under IRC Section 988(e) and Revenue Ruling 90-79, a mortgage on a personal residence is excluded from the ordinary income treatment that Section 988 applies to many foreign currency transactions. Instead, exchange-rate movement on the debt is measured under general capital gain and loss rules. That distinction is why a phantom can appear: you can owe tax on a gain from the debt even though you never received extra cash.
The two-instrument trap
Your Swiss home and your Swiss mortgage are separate for US tax purposes. Section 121 may shelter up to $250,000 of gain on the property ($500,000 for married filing jointly), but it does not shelter foreign currency gain or loss on the debt.
How the gain or loss shows up
If the franc weakens against the dollar after you take out the mortgage, repaying or refinancing the loan costs fewer dollars than the dollar value of the original debt, and that spread can be a reportable capital gain. If the franc strengthens, the resulting loss is generally personal and may not be deductible. Either way, the result is reported on Form 8949 as a capital item—not as ordinary income and not sheltered by the home-sale exclusion. Tax software rarely surfaces this automatically.
- Track the CHF/USD rate at origination and at each repayment, refinance, or sale date.
- Treat the mortgage debt separately from the home for US tax analysis.
- Model the debt's foreign currency gain or loss before you refinance or make a large amortization.
- Keep records of the original loan amount in francs and the dollar value of every payment.
What the dropped relief would have changed
The August 4 discussion draft would have amended Section 165(c) to allow deductions for foreign currency losses tied to a mortgage on a principal residence abroad, and losses on the sale of that residence, against gain recognized. It would also have raised the Section 988(e) personal transaction exemption from $200 to $1,000 and indexed it to inflation. Because the provisions were left out of the Chairman's Mark, those changes are not law. The current rules remain in force.
What this means for your Swiss mortgage
If you already own a Swiss home or are planning to buy, the planning question is not whether to avoid a franc mortgage—it's how to structure repayment so you don't create an avoidable tax surprise. Indirect amortization strategies, refinancing, and selling all interact with the debt's dollar basis. Our guide to Swiss mortgage amortization for Americans walks through the direct and indirect methods. Read it before you decide how to pay down the loan.
Your next step
The rules are technical, but you don't need to become a Section 988 expert. Know that the debt is a separate tax position, track the exchange rates, and get personal advice before a repayment, refinance, or sale. Educational information shows you the landscape; individual decisions depend on your full tax picture.