Company: BLLN
Filing Date: 2025-09-17
Form Type: DRS/A
Source: 0001193125-25-206347
Chunk: 309

Company: BillionToOne, Inc.
Filing Date: 2025-09-17
Form: DRS/A
Chunk 309
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 other disposition of Class A common stock Subject to the discussion below under the section titled “—Backup withholding and information reporting” and “—Foreign Account Tax Compliance Act,” non-U.S.holders will generally not be subject to U.S. federal income tax on any gains realized on the sale, exchange or other disposition of our Class A common stock unless:

| • |     | the gain (1) is effectively connected with the conduct by the non-U.S. holder                                                                                                               
 of a U.S. trade or business and (2) if required by an applicable income tax treaty between the United States and the non-U.S. holder’s country of residence, is attributable to a permanent 
 establishment or fixed base maintained by the non-U.S. holder in the United States (in which case the special rules described below apply);                                                 |

| • |     | the non-U.S. holder is an individual who is present in the United States for 183                                                                                                                                                                     
 days or more in the taxable year of the sale, exchange or other disposition of our Class A common stock, and certain other requirements are met (in which case the gain would be subject to a flat 30% tax, or such reduced rate as may be specified 
 by an applicable income tax treaty, which may be offset by U.S. source capital losses, even though the individual is not considered a resident of the United States), provided that the non-U.S. Holder has                                          
 timely filed U.S. federal income tax returns with respect to such losses; or                                                                                                                                                                         |

| • |     | the rules of the Foreign Investment in Real Property Tax Act (FIRPTA), treat the gain as effectively connected with a U.S. 
 trade or business.                                                                                                         |

The FIRPTA rules may apply to a sale, exchange or other disposition of our Class A common stock if we are, or were within the shorter of the five-year period preceding the disposition and the non-U.S.holder’s holding period, a U.S. real property holding corporation, or USRPHC. In general, we would be a USRPHC if interests in U.S. real property comprised at least half of the value of our worldwide real property and our other assets held for use in a trade or business. Although there can be no assurances, we believe that we are not currently and will not become a USRPHC for U.S. federal income tax purposes, and the remainder of this discussion so assumes. However, because the determination of whether we are a US