Company: BLLN
Filing Date: 2025-06-20
Form Type: DRS
Source: 0000950123-25-006095
Chunk: 191

Company: BillionToOne, Inc.
Filing Date: 2025-06-20
Form: DRS
Chunk 191
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 Reimbursement sources and status We receive reimbursement from several distinct sources:

| • |     | Commercial third-party payors, including insurance companies and health maintenance organizations |

| • |     | Government payors, state Medicaid programs, and Medicare (starting in 2025) |

| • |     | Employee benefits health plans |

| • |     | Individual patients, who represent a small amount of our revenue |

Commercial payors We have significantly expanded our in-networkstatus with commercial insurers, including several of the largest national payors. We expect this in-networkexpansion to continue driving higher ASPs and enhance revenue predictability, due to the contracts establishing agreed-upon rates. Beyond our contracted rate agreements, we submit claims for reimbursement and receive associated payments from commercial insurers on a non-contractedbasis as necessary. The amount of reimbursement allowed and collected outside of network contract rates with commercial insurers is subject to greater variability and less predictability. 152

In prenatal, our carrier and aneuploidy tests are broadly covered by most major insurance providers, and we have broad
reimbursement for tests we provide. Our sgNIPT and fetal antigen NIPT have variable coverage, with certain payors providing reimbursement, creating opportunities for ASP growth as coverage expands. For our oncology products, Northstar Select has
gained coverage from several commercial insurers. Northstar Response, while newer to market, is already reimbursed by certain commercial insurers, achieving a level of ASP that already provides positive contribution margins.

Medicare

We have obtained Medicare coverage for both our prenatal and
oncology testing services. In April 2025, our Northstar Select test received a positive coverage decision and Z-code through the MolDX program administered by Palmetto GBA.

For our prenatal tests, Medicare provides coverage for patients who meet the Medicare eligibility criteria; however, this represents a very small portion of our prenatal
test volume given the demographics of pregnant patients. For our oncology portfolio, Medicare coverage is crucial given the higher prevalence of cancer in the Medicare-eligible population.

We continue to advance our evidence development strategy for Northstar Response, which requires additional clinical validity and utility data for Medicare coverage. Our
flagship “NORTH” study, along with other ongoing clinical studies, is designed to generate the evidence necessary for Medicare coverage, initially focusing on immunotherapy and immunotherapy-combination therapy applications.

Medicaid

We have enrolled in over 40 state Medicaid programs across the
United States. These enrollments are critical for our prenatal test ASP