Company: BLLN
Filing Date: 2025-10-07
Form Type: S-1
Source: 0001193125-25-233697
Chunk: 44

Company: BillionToOne, Inc.
Filing Date: 2025-10-07
Form: S-1
Chunk 44
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 in information, pre-authorization and other billing requirements among 
 payors;                                                                            |

| • |     | changes to codes and coding instructions governing our tests; |

| • |     | incorrect or missing billing information; and |

| • |     | the resources required to manage the billing and claim appeals process. |

These billing complexities and the related uncertainty in obtaining payment for our tests could negatively affect our revenue and cash flow, our ability to achieve or maintain profitability and the consistency and comparability of our results of operations. In addition, if claims for our tests are not submitted to payors on a timely basis, or if we fail to comply with applicable billing requirements, it could have an adverse effect on our revenue and our business. In addition, the coding procedure used by third-party payors to identify various procedures, including our tests, during the billing process is complex, does not adapt well to our tests and may not enable coverage and adequate reimbursement rates. Third-party payors require us to identify the test for which we are seeking reimbursement using a Current Procedural Terminology (CPT) code. CPT coding plays a significant role in how our tests test are reimbursed both from commercial and governmental payors. The CPT code set is maintained by the American Medical Association (AMA). In cases where there is not a specific CPT code to describe a test, the test may be billed under an unlisted molecular pathology procedure code or through the use of a combination of single gene CPT codes, depending on the payor. PAMA authorized the adoption of new, temporary billing codes and unique test identifiers for FDA-clearedor approved tests as well as advanced diagnostic laboratory tests. The AMA has created a new section of CPT codes, Proprietary Laboratory Analyses codes (PLA), to facilitate implementation of this section of PAMA. We received PLA codes for most of our tests in 2024. Because billing third-party payors for our tests is an unpredictable, challenging, time-consuming and costly process, we may face long collection cycles and the risk that we may never collect at all, either of which 26

could adversely affect our business, results of operations and financial condition, and we may have to increase collection efforts and incur additional costs. Additionally, because next
generation genomic sequencing is a rapidly evolving area of medicine, and because clinical treatment guidelines continue to develop, any changes to, or interpretations of, applicable billing and coding guidance, rules, policies, and procedures may
impact our business. There is no guarantee