Company: BLLN
Filing Date: 2025-10-17
Form Type: S-1/A
Source: 0001193125-25-242632
Chunk: 46

Company: BillionToOne, Inc.
Filing Date: 2025-10-17
Form: S-1/A
Chunk 46
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 for and the amount of Medicaid reimbursement. As a result of all of these factors, some state Medicaid programs may only reimburse our testing at a low dollar amount, or not at all. Low or zero-dollarMedicaid reimbursement rates for our tests could have an adverse effect on our business and revenue. Our billing and claim processing are complex and time-consuming, and any delay in submitting claims or failure to comply with applicable billing requirements could hinder collection and have an adverse effect on our revenue. Billing for our tests is complex, time-consuming and expensive. Depending on the billing arrangement and applicable law, we bill various payors, such as Medicare, Medicaid, health plans, insurance companies and patients, all of which may have different billing requirements. Several factors make the billing process complex, including:

| • |     | differences between the list prices for our tests and the reimbursement rates of payors; |

| • |     | compliance with complex federal and state regulations related to billing government healthcare programs, including Medicare 
 and Medicaid, to the extent our tests are covered by such programs;                                                         |

| • |     | differences in coverage among payors and the effect of patient co-payments or co-insurance; |

| • |     | differences 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