如果您拥有海外共同基金或境外 ETF，在美联储国税局（IRS）眼中，这些资产绝大部分被归类为 PFIC（被动外国投资公司）。在我们上一篇文章中已提到过一个案例来帮助您理解PFIC的概念，这一次我们将关注于它的一种PFIC特殊的申报方式。
美国政府对这类境外投资设有极其严苛的惩罚性税则。如果您放任不管，即使您没有卖出任何股票，也可能被课以最高级别的普通收入税（Ordinary Income Tax），并加上年复利的利息罚款。为了摆脱这个陷阱，许多投资人会选择一种特殊的申报方式，叫做 Mark-to-Market（MTM，市场计价法）。
什么是 MTM（标记为市场计价）？这是一种“年终虚拟结算”的申报方式。您无需等到真正卖出基金，而是在每年 12 月 31 日假装把基金按市价卖掉。如果市场上涨，您就为这笔“账面未实现收益”缴纳普通收入税；如果市场下跌，您则可以申报税务扣除额（前提是有 Unreversed Inclusion，即“已缴税假设收入”）。每次您为账面收益缴税后，您的税务基数（Basis）（国税局为您追踪的成本基准）就会同步调高。
权衡利弊：MTM 选择权的优缺点
优点
- 免除恐怖的追溯性利息罚款： 若按国税局预设规则（Section 1291），当您未来卖出基金时，IRS 会假定您的利润是持有期间均匀赚得的，并对过去每一年的虚拟利润征收最高税率，再加算每年复利计算的利息罚款。选择 MTM 可以完全免除这笔利息。
- 享有独特的年度亏损扣除： 如果基金当年下跌，MTM 允许您申报普通扣除额来直接抵扣您当年的个人薪资收入（前提是有 Unreversed Inclusion），这是美国本土股票基金做不到的。
缺点
- 为“未入袋的财富”提前掏出现金： 即使您没有卖出基金、没有拿到一分钱现金，只要年底账面数字上涨，您就必须用口袋里的真金白银去为“未实现的账面增值”缴税。
- 适用较高的普通收入税率： 无论是每年的账面增值，还是最终卖出时的利润，通通必须按照您当年的普通收入税率（最高可达 37%）课税，完全无法享受美国本土投资所拥有的较低长期资本利得税率（0%/15%/20%）。
- 繁琐的历史记账： 您必须每年严格追踪、动态调整您的税务基数。
“已缴税假设收入”（Unreversed Inclusion）规则
要理解跨年交易，您必须了解国税局的“已缴税假设收入”机制。
只有当您在市场上涨、为“假设收入”缴税时，国税局才会记录您的已缴税假设收入额度。在持有基金的年度里，如果市场下跌，您可以用已缴税假设收入额度来换取“普通亏损扣除额”（Ordinary Loss）。
网上流传着一个巨大的误解：有些文章声称，如果外国基金的价格跌破了您的基数，任何超过您过去已缴税假设收入额度的亏损，都会“永久消失”。为了彻底厘清这一点，我们直接用一个跨年度持有并交易的案例来拆解。
跨年交易案例实操：三年投资周期全记录
假设您在第一年以 $10,000 美元买入一档境外基金，持有度过第二年，并在第三年中旬决定全盘卖出。
第一年：账面增值（继续持有）
- 12 月 31 日年底市值： 基金涨到了 $13,000。
- 税务操作： 您产生了 +$3,000 的账面收益，今年必须为此申报并缴纳普通收入税。
- 账簿调整： 您的税务基数（成本基准）调高至 $13,000，同时获得 $3,000 的已缴税假设收入额度。
第二年：账面下跌（继续持有）
- 12 月 31 日年底市值： 市场回落，基金跌到 $11,000。
- 税务操作： 国税局对比您去年的基数（$13,000），显示账面亏损 -$2,000。此时您已记录了 $3,000 的已缴税假设收入额度，因此您可以在第二年的税单上申报 -$2,000 的普通扣除额。（注意：此时基金尚未卖出）
- 账簿调整： 已缴税假设收入额度还剩 $1,000，您的税务基数下调到 $11,000。
第三年：正式卖出清仓（套现） 在第三年的 7 月，您决定把基金全部卖掉换成现金。您最终的税务结果，完全取决于您的卖出价与最后阶段基数（$11,000）之间的对比。会出现以下两种情况：
- 情景 A：您获利卖出（产生收益）
- 卖出价： $15,000。
- 税务结果： 拿卖出价 $15,000 对比最后基数 $11,000，您获得了 +$4,000 的最终利润。
- 适用税率： 因为您当年选择了 MTM，这笔跨年赚到的 $4,000 最终利润将全部被视为“普通收入”（Ordinary Income），按照您当年的个人薪资税率缴税，无法享受较低的资本利得税率。
- 情景 B：您严重亏损卖出
- 卖出价： $8,000。
- 税务结果： 拿 $8,000 对比最后基数 $11,000，您的实际总亏损为 -$3,000。
- 亏损如何拆分： 此时您的已缴税假设收入额度还剩 $1,000。国税局会在您最终的税单上将亏损一分为二：用尽剩下的已缴税假设收入额度 $1,000 算作普通亏损，而超出额度的剩余 $2,000 亏损自动转化为资本亏损（Capital Loss）（用于抵扣其他投资盈利）。
这项最终保障明确记载于美国财政部官方税法 Treasury Regulation § 1.1296-1(c)(4)(ii) 中。您的亏损绝不会被国税局凭空抹去，只是在最终结算时换了个形式帮您省税。
If you own foreign mutual funds or offshore ETFs, the IRS classifies the vast majority of these assets as PFICs (Passive Foreign Investment Companies). We previously discussed a case study in our last article to help you understand the concept of PFICs; in this article, we will focus on a special PFIC reporting method.
The U.S. government imposes extremely harsh, punitive tax rules on these investments. If you leave them unmanaged, even without selling a single share, you may be subject to the highest Ordinary Income Tax rates, plus compounding interest penalties. To escape this trap, many investors choose a special reporting method called Mark-to-Market (MTM).
What is MTM?
MTM is an “annual virtual settlement” reporting method. You do not need to wait until you actually sell the fund; instead, you pretend to sell the fund at its market value on December 31st each year. If the market rises, you pay ordinary income tax on this “unrealized paper gain.” If the market falls, you can claim a tax deduction (provided you have an Unreversed Inclusion). Each time you pay tax on paper gains, your Tax Basis (the cost baseline tracked for the IRS) is adjusted upward accordingly.
Weighing the Pros and Cons of MTM
Advantages
- Avoids Punitive Interest Charges: Under default IRS rules (Section 1291), when you eventually sell the fund, the IRS assumes your profit was earned evenly over the entire holding period, taxing those “virtual” annual profits at the highest rates and adding compounded interest penalties. Choosing MTM completely exempts you from these interest charges.
- Unique Annual Loss Deduction: If the fund declines in value during the year, MTM allows you to claim an ordinary loss deduction to offset your personal wage income (provided you have an Unreversed Inclusion). This is a benefit not available with U.S.-based stock funds.
Disadvantages
- Paying Cash for “Paper Wealth”: Even if you have not sold the fund and have not received any cash, you must use real money to pay taxes on “unrealized gains” if the market value rises by year-end.
- Higher Ordinary Income Tax Rates: Whether it is annual paper gains or final profits upon sale, all income is taxed at your ordinary income tax rate (up to 37%). You cannot utilize the lower Long-Term Capital Gain rates (0%/15%/20%) available for U.S.-based investments.
- Complex Record Keeping: You must strictly track and dynamically adjust your tax basis every year.
The “Unreversed Inclusion” Rule
To understand multi-year trading, you must understand the IRS mechanism of Unreversed Inclusion. The IRS only records your “unreversed inclusion” amount when the market rises and you pay tax on those “assumed gains.” During years when you hold the fund, if the market falls, you can use this inclusion balance to claim an “Ordinary Loss” deduction.
There is a major misconception circulating online: some articles claim that if the foreign fund’s price falls below your basis, any loss exceeding your past unreversed inclusions “permanently disappears.” To clarify this, let’s break it down with a multi-year holding and trading case.
Multi-Year Trading Case Study: A Three-Year Investment Cycle
Suppose you buy an offshore fund for $10,000 in Year 1, hold it through Year 2, and decide to liquidate the entire position in the middle of Year 3.
Year 1: Paper Gain (Holding)
- Dec 31 Year-End Market Value: The fund rises to $13,000.
- Tax Action: You generate a +$3,000 paper gain and must report and pay ordinary income tax on it this year.
- Basis Adjustment: Your tax basis is adjusted up to $13,000, and you gain $3,000 in unreversed inclusion balance.
Year 2: Paper Loss (Holding)
- Dec 31 Year-End Market Value: The market retreats, and the fund falls to $11,000.
- Tax Action: Comparing the market value to last year’s basis ($13,000) shows a paper loss of -$2,000. Since you have a $3,000 unreversed inclusion balance, you can claim an ordinary loss deduction of -$2,000 on your tax return. (Note: The fund has not been sold at this point.)
- Basis Adjustment: Your unreversed inclusion balance remains at $1,000, and your tax basis is adjusted down to $11,000.
Year 3: Final Liquidation In July of Year 3, you sell the entire fund for cash. Your final tax outcome depends on the sale price versus the final basis ($11,000). There are two scenarios:
- Scenario A: Selling at a Profit
- Sale Price: $15,000.
- Tax Outcome: Comparing the $15,000 sale price to the $11,000 final basis, you have a final profit of +$4,000.
- Tax Rate: Because you elected MTM, this $4,000 profit is treated as “Ordinary Income,” taxed at your personal wage tax rate, with no access to lower capital gains rates.
- Scenario B: Selling at a Significant Loss
- Sale Price: $8,000.
- Tax Outcome: Comparing $8,000 to the $11,000 final basis, your total actual loss is -$3,000.
- Splitting the Loss: With $1,000 of unreversed inclusion balance remaining, the IRS splits the loss: the remaining $1,000 balance is used as an ordinary loss, while the excess $2,000 loss is automatically converted into a Capital Loss (which can be used to offset other investment gains).
This final protection is explicitly documented in the U.S. Treasury Regulation § 1.1296-1(c)(4)(ii). Your losses will never be wiped out by the IRS; they are simply reconciled in a way that helps you save on taxes during final settlement.