Company: BLLN
Filing Date: 2025-10-17
Form Type: S-1/A
Source: 0001193125-25-242632
Chunk: 316

Company: BillionToOne, Inc.
Filing Date: 2025-10-17
Form: S-1/A
Chunk 316
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 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 USRPHC depends on the fair market value of our U.S. real property interests relative to the fair market value of our U.S. and worldwide real property interests plus our other assets used or held for use in a trade or business, there can be no assurance that we will not become a USRPHC in the future. Even if we are or were to become a USRPHC gain arising from the sale or other taxable disposition by a non-U.S.holder will not be subject to U.S. federal income tax if our Class A common stock is “regularly traded,” as defined by applicable Treasury Regulations, on an established securities market, and such non-U.S.holder owned, actually and constructively, 5% or less of our Class A common stock throughout the shorter of the five