Because you held no PFIC shares on December 31, 2025, you cannot make a new 2025 MTM election or use sale-date values on lines 10a and 10b.
“I moved to the US in October 2025 and am filing jointly for the whole year. I sold all my PFICs by the end of 2025. How do I fill out Part 4, lines 10a and 10b on Form 8621 for a Mark-to-Market (MTM) election, and what dates do I use for adjusted basis and FMV since I didn't hold them at year-end?”
Summary
You do not need to invent a December 31 value. The key is simply whether an MTM election was already valid before the sales.
The correct route depends on whether a valid section 1296 election was already in effect before you sold the shares.
You cannot make a new 2025 for shares sold before December 31, 2025: the regulation requires ownership of on the last day of the tax year. Lines 10a and 10b are therefore not applicable—leave them blank rather than entering zero, an October arrival value, or sale-date values. [26 CFR 1.1296-1(h)(1)(i); 2025 Form 8621 Instructions, Part IV]
If a valid section 1296 election existed from an earlier year, it generally continues until revoked or terminated. Because nothing remained at year-end, lines 10a and 10b are still not applicable; report each 2025 disposition on lines 13a through 14c, using and on that sale or disposition date. Prior MTM income increases basis and prior allowed MTM deductions decrease it. [26 CFR 1.1296-1(d)(1), (h)(2)(i); 2025 Form 8621 Instructions, lines 13–14c]
If no valid MTM or other PFIC election applied, the sold shares were not section 1296 stock. Do not complete Part IV as an MTM sale; report recognized disposition gain for the in Part V, line 15f, and complete the line 16 allocation on an attached sheet. A disposition loss is not taken into account under section 1291, although another Code provision may recognize it. [2025 Form 8621 Instructions, Part V, lines 15f–16]
Apply the route separately to every because the IRS requires a separate Form 8621 for each PFIC held directly or indirectly.
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Next steps
These steps place every sale on the correct part of Form 8621 and keep year-end values off lines where they do not belong.
Before entering amounts
Classify each PFIC by its prior election history
For each PFIC, determine whether a valid section 1296 election was already in force before its 2025 sale. A prior election generally continues until revoked or terminated; without one, shares sold before December 31 cannot receive a new 2025 election. [26 CFR 1.1296-1(h)]
Requirements
No valid prior MTM or other PFIC election
Prepare the default-regime form when no prior election existed
Use the December 2025 Form 8621 at https://www.irs.gov/pub/irs-prior/f8621--2025.pdf. Do not make Election C or enter sale-date amounts on lines 10a and 10b; report recognized disposition gain on Part V, line 15f, and prepare the line 16 allocation sheet. A disposition loss is outside section 1291 and must be handled under any other applicable loss rule. [2025 Form 8621 Instructions, Part V]
Requirements
Only if the election already existed
Report sales covered by an existing MTM election
Leave lines 10a and 10b blank because no stock remained at year-end. Complete lines 13a through 14c: line 13a uses on the sale or disposition date, and line 13b uses on that same date after prior MTM adjustments. For multiple dispositions, attach a statement for each sale using the lines 13–14c format. [2025 Form 8621 Instructions, Part IV; 26 CFR 1.1296-1(d)]
Requirements
At filing
Attach every Form 8621 to the joint return
Attach the Forms 8621 to the 2025 joint Form 1040 and file them together; Form 8621 has no separate filing destination when an income-tax return is required. The ordinary Form 1040 deadline was April 15, 2026, and Form 8621 follows any valid extended return deadline. If no extension or other postponement applies, file the completed return now. [2025 Form 8621 Instructions, “When and Where To File”; 2025 Form 1040 Instructions]
Requirements
Legal sources
This answer is grounded in the December 2025 IRS Form 8621 instructions, the Internal Revenue Code, and current Treasury regulations.
2025 Instructions for Form 8621
This separates year-end MTM entries from dispositions made during the year.
Part IV, pages 12–13
A shareholder that has made a mark-to-market election under section 1296 with respect to PFIC stock completes lines 10a through 12 with respect to PFIC stock that the shareholder holds at the close of its tax year, and lines 13a through 14c, with respect to PFIC stock that it sold or disposed of during its tax year.
26 CFR 1.1296-1
This is why shares sold before December 31 cannot receive a new 2025 MTM election.
(h)(1)(i)
A United States person that owns marketable stock in a PFIC, or is treated as owning marketable stock under paragraph (e) of this section, on the last day of the taxable year of such person, and that wants to make a section 1296 election, must make a section 1296 election for such taxable year on or before the due date (including extensions) of the United States person's income tax return for that year.
2025 Instructions for Form 8621
A sale covered by an existing MTM election uses sale-date—not year-end—values.
Part IV, lines 13–14c
Complete lines 13 through 14c if you sold or otherwise disposed of any section 1296 stock during the tax year. If the fair market value of the stock on the date of sale or disposition (line 13a) is more than the U.S. person's adjusted basis in the stock on the date of sale or disposition (line 13b), the line 13c excess is a gain and is treated as ordinary income.
26 CFR 1.1296-1
This establishes the continuing-election branch and the MTM basis adjustments used on a sale.
(d)(1), (h)(2)(i)
A section 1296 election will apply to the taxable year for which such election is made and remain in effect for each succeeding taxable year unless such election is revoked or terminated pursuant to paragraph (h)(3) of this section. The adjusted basis of the section 1296 stock shall be increased by the amount included in the gross income of the United States person under paragraph (c)(1) of this section with respect to such stock, and decreased by the amount allowed as a deduction to the United States person under paragraph (c)(3) of this section with respect to such stock.
2025 Instructions for Form 8621
This gives the default section 1291 treatment when no valid MTM election covered the shares.
Part V, line 15f
Gain recognized on the disposition of stock of a section 1291 fund is treated as an excess distribution. Loss realized on the disposition of stock of a section 1291 fund is not taken into account under section 1291 and thus, for example, does not reduce the amount of total gain subject to section 1291. However, the loss may be recognized under another provision of the Code and reported accordingly.
26 USC 6013(g)-(h)
A qualifying whole-year joint election makes the newcomer a U.S. resident for chapter 1 throughout 2025.
(g)(1), (h)(1)
then the individual referred to in subparagraph (A) shall be treated as a resident of the United States for purposes of chapter 1 for all of such taxable year, and for purposes of chapter 24 (relating to wage withholding) for payments of wages made during such taxable year.
26 CFR 1.1296-1
The newcomer first-day basis rule is confined to section 1296 stock and is not a general arrival-date basis rule.
(d)(5)(i)
If any individual becomes a United States person in a taxable year beginning after December 31, 1997, solely for purposes of this section, the adjusted basis, before adjustments under this paragraph (d), of any section 1296 stock owned by such individual on the first day of such taxable year shall be treated as being the greater of its fair market value or its adjusted basis on such first day.
2025 Instructions for Form 8621
Each PFIC needs its own form, attached to the income-tax return by the applicable return deadline.
Who Must File; When and Where To File
A separate Form 8621 must be filed for each PFIC in which stock is held directly or indirectly. Attach Form 8621 to the shareholder's tax return (or, if applicable, partnership or exempt organization return) and file both by the due date, including extensions, of the return at the Internal Revenue Service Center where the tax return is required to be filed.
2025 Instructions for Form 1040
This was the standard deadline for the 2025 calendar-year individual return.
When and Where Should You File?
File Form 1040 or 1040-SR by April 15, 2026.
These are the official rules as published on the cited dates; tax forms and rules can change.
This is general information about official tax processes, not legal advice, and SettleKit is not a law firm.
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