Company: BLLN
Filing Date: 2025-10-07
Form Type: S-1
Source: 0001193125-25-233697
Chunk: 43

Company: BillionToOne, Inc.
Filing Date: 2025-10-07
Form: S-1
Chunk 43
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 services resides in order for us to be reimbursed by a state’s Medicaid program, including under a Medicaid managed care plan. Furthermore, in certain states that have implemented managed care organizations (MCOs) that are typically operated by commercial third-party payors, we may also need to contract with one or more MCOs as a participating network provider for us to be reimbursed for testing services that we provide to a Medicaid beneficiary in such state.

| 22 |     | Our carrier screen test is not covered by Alabama, Michigan, or Nevada, and our aneuploidy test is not covered by Nebraska, Nevada or Utah. State Medicaid coverage for our RhD and fetal antigen tests is currently 
 uncommon. Our oncology test are covered at the federal level by Medicare. Medicaid coverage for our oncology tests is less relevant, as the vast majority of cancer patients do not have Medicaid coverage.          |

25

Our Union City laboratory, where our prenatal tests are processed, is currently enrolled as a Medicaid provider in over 40 states. However, even if we are recognized as a Medicaid provider in a state, the Medicaid reimbursement amounts are sometimes as low, or lower, than the Medicare reimbursement rate. In addition, from time to time we receive requests from state Medicaid programs seeking information or documents to determine eligibility 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