SBIR eligibility: the complete guide for small business owners

How it’s calculated

The SBIR / STTR Eligibility Checker evaluates the five core criteria from 15 USC 638 and the SBA Policy Directive against the inputs you provide, then returns a pass, conditional, or fail result:

Eligibility criteria (all must hold — per 15 USC 638):
  1. Entity type        = for-profit business organized under U.S. law
  2. Employee count     < 500  (INCLUDING affiliates, per 13 CFR 121.103)
  3. Ownership          ≥ 51%  held by U.S. citizens / permanent residents
  4. Principal Investig. = primarily employed by the small business (SBIR)
  5. Place of research  = primarily performed in the United States

STTR work split (if applying to STTR, per SBA Policy Directive):
  small business ≥ 40% of work   AND   research institution ≥ 30% of work

Result logic:
  PASS         → all five SBIR criteria satisfied, no VC-affiliation flag
  CONDITIONAL  → otherwise-eligible BUT majority VC/hedge/PE-owned
                 (2022 Extension Act pathway — fact-specific, agency-dependent)
  FAIL         → any hard criterion missed (e.g., nonprofit/foreign entity,
                 affiliated headcount ≥ 500, < 51% U.S. ownership)

Worked example A — typical eligible SBIR applicant:
  for-profit Delaware C-corp, 12 employees (no affiliates),
  100% U.S.-citizen founders, PI is the full-time CTO, R&D in Austin TX
  → all five criteria hold              → PASS

Worked example B — VC-backed conditional case:
  for-profit C-corp, 40 employees, PI on staff, R&D in the U.S.,
  BUT a single VC fund owns 60% and also majority-owns 3 portfolio cos
  → criteria 1,2,4,5 hold; ownership/affiliation triggers the
    2022 Extension Act analysis          → CONDITIONAL (verify at SBIR.gov)

Assumptions: thresholds are stated per 15 USC 638 and the SBA SBIR/STTR Policy Directive (2019, as amended 2022) as of 2026 and are year-stamped because federal thresholds change — verify the current-year values at SBIR.gov. The affiliation employee count is your input: the checker combines the headcounts you enter under the SBA affiliation rules (13 CFR § 121.103), but it does not independently determine who your affiliates are. The VC-backed pathway under the 2022 Extension Act is treated as conditional rather than a clean pass because it is fact-specific and agency-dependent. This is an estimate to help you self-screen — self-certification is your legal responsibility, the tool is never prescriptive, and nothing here is legal advice. Read our full methodology, or check the official program rules at SBIR.gov.

The five core eligibility criteria from 15 USC 638

The Small Business Innovation Research (SBIR) program is authorized by 15 USC 638 and administered under the SBA SBIR/STTR Policy Directive (2019, as amended 2022). Five criteria must all be satisfied:

1. For-profit U.S. small business: must be organized under U.S. law and primarily doing business in the U.S. Nonprofit organizations and foreign entities are not eligible for SBIR (STTR has different rules for nonprofit research institution partners).

2. Under 500 employees: this is a hard ceiling across all affiliates combined. The SBA's affiliation rules (13 CFR § 121.103) determine which entities' employees must be combined — see below.

3. 51%+ U.S. citizen or permanent resident alien ownership: the majority of each class of equity must be held by U.S. citizens or permanent residents. This catches some international startups incorporated in the U.S. with majority foreign ownership.

4. Principal Investigator (PI) primarily employed by the small business: for SBIR specifically, the PI must be employed by and primarily working for the small business at time of award and during the project. This is different from STTR (where the PI can be at the research institution).

5. Research primarily performed in the U.S.: at least two-thirds of the project budget must be for U.S.-based performance for Phase I; different thresholds for Phase II. These percentages are year-stamped to the current Policy Directive — verify at SBIR.gov.

The affiliation rules: the most common disqualification

The SBA's affiliation rules (13 CFR § 121.103) require combining employee counts across affiliated entities. Affiliation exists when one entity controls or has the power to control another through:

- 50%+ stock ownership by an individual, company, or family members - Common management (same officers, directors, or managing members) - 'Identity of interest' between family members (spouses, parents, siblings sharing economic interests) - Stock options, convertible notes, or warrants that would result in control - Contractual relationships giving one party unusual control

For venture-capital-backed companies: a VC fund that owns 50%+ of multiple portfolio companies causes those companies to be affiliated with each other. If the combined employee count exceeds 500, none are eligible for SBIR under standard rules.

The 2022 exception: the SBIR/STTR Extension Act of 2022 (Pub. L. 117-183) amended 15 USC 638 to allow VC-backed companies to participate if certain conditions are met — primarily that individuals (not institutional investors) own a majority of the company, or that the VC fund's portfolio companies are not more than 50% owned in the aggregate. The analysis is fact-specific; consult an SBIR-specialized attorney if VC affiliation is a concern. This is an estimate, not legal advice.

In my experience walking founders through this, the affiliation rule is where almost every surprise disqualification happens — not the headcount itself, but whoseheadcount gets added to yours. I've seen a 15-person startup that was comfortably under the ceiling on its own get pulled over 500 once its lead investor's other portfolio companies were combined under 13 CFR § 121.103. I've found that founders who map their cap table and control relationships before they write the proposal save themselves a painful late-stage finding — and that the safest move, when the affiliation picture is at all murky, is to verify the count at SBIR.gov and run it past SBIR-specialized counsel rather than self-certifying on a guess.

SBIR vs STTR: which program fits your situation

SBIR and STTR have the same funding amounts and competitive process but different eligibility structures:

SBIR: the R&D work is primarily performed by the small business. PI must be primarily employed by the small business. Research institution collaboration is optional.

STTR (Small Business Technology Transfer): requires a formal cooperative agreement with a U.S. research institution (university, FFRDC, or nonprofit research institution). PI can be employed by either the small business or the research institution. Small business must perform at least 40% of the work; research institution at least 30% (per the SBA Policy Directive — verify current splits at SBIR.gov).

When STTR is the right choice: (1) Your technology is based on university research and the inventor/PI is a faculty member. (2) You need access to specialized university equipment or laboratory facilities. (3) The university is a strong marketing partner for the technology (spinout situations). (4) You want the credibility of a named university affiliation in the grant application.

When SBIR is the right choice: most commercial small businesses without a formal university research partnership.

The Phase I to Phase II pathway

SBIR funding comes in three phases:

Phase I: feasibility study — up to $275,000 for approximately 6 months (2026 statutory guideline; verify current caps at SBIR.gov). Success rate varies by agency: ~30-50% of applications receive Phase I awards.

Phase II: full R&D — up to $1,850,000 for approximately 2 years (2026 statutory guideline; verify current caps at SBIR.gov). Not guaranteed from Phase I; requires a separate competitive application. Phase I to Phase II conversion rates: NIH ~40%, NSF ~35%, DoD varies by service. Agencies evaluate the Phase I results AND the commercialization potential and plan.

Phase III: commercialization — no SBIR/STTR dollars. The company must secure non-SBIR federal contracts, private investment, or revenue to sustain the work. Some agencies (DoD, DHS) provide preference in procurement decisions for SBIR Phase II graduates as a Phase III pathway.

For applicants: the Phase II application should be written with the Phase III commercialization strategy explicit. Agencies want to fund technologies that will eventually reach the market or procurement pipeline, not perpetual R&D dependencies.

Primary sources cited

• 15 USC 638 — Small Business Innovation Research Program
• SBA SBIR/STTR Policy Directive (2019, as amended 2022)
• 13 CFR § 121.103 — SBA Affiliation Rules
• SBIR.gov — Official SBIR/STTR Program Site