Sequential Phase II and Phase II enhancements, explained

A Small Business Innovation Research (SBIR) Phase II is not always the last SBIR-funded award on a project. The statute and the U.S. Small Business Administration (SBA) directive allow one more Phase II for the same work, and agencies layer their own supplements on top: Phase IIB, Phase II enhancement, Phase II options, STRATFI, TACFI, and, since April 2026, strategic breakthrough awards. Each is SBIR money with SBIR limits. The rule for the second award is section 4(b)(5) of the SBIR/STTR Policy Directive, effective May 3, 2023, and 15 U.S.C. 638(ff)(1). The rule for supplements is section 4(b)(6).

This post explains the sequential Phase II, the supplements as the Department of Defense (DoD), the Navy, the Air Force, the Army, the National Institutes of Health (NIH), and the National Science Foundation (NSF) define them, the matching funds each requires, the aggregate limits, and how all of them differ from Phase III. For the base phases, see SBIR Phase I, II, and III, explained.

Sequential Phase II under the directive and the statute

Subsection (ff) of the statute, titled "Additional SBIR and STTR awards," gives the express authority. Paragraph (1) says a small business that receives a Phase II SBIR or STTR award for a project remains eligible to receive one additional Phase II SBIR or STTR award for continued work on that project. Paragraph (2) requires the agency head to verify that the work has not been funded under another agency's SBIR or STTR program.

Section 4(b)(5) of the directive implements it: a Phase II awardee may receive one additional, sequential Phase II award to continue the work of an initial Phase II, and the sequential award "has the same guideline amounts and limits as an initial Phase II award." That phrase matters. Under section 7(i)(1), a Phase II may not exceed the $1,000,000 guideline by more than 50 percent, so the sequential award carries its own guideline and its own 50 percent headroom rather than sharing the first award's. Section 4(b)(7) adds a cross-agency route: a firm with a Phase I from one agency may receive a subsequent Phase II from another agency if each makes a written determination that the topics are the same. Public Law 119-83 refers to that route as subsection (bb)(1).

The directive also describes a third Phase II. Section 4(b)(1)(iii), SBIR only, requires agencies to implement a Commercialization Assistance Pilot Program under which a firm that has received a Phase II and a sequential Phase II from the agency may apply for a third Phase II for further commercialization. The award may not exceed the limitation on award size, must be disbursed during the performance of a Phase II, may use up to 5 percent of the agency's SBIR funds, and requires matching from an eligible third party equal to the amount of the award, excluding fees. Eligible investors include another small business, venture capital firms, individual investors, and non-SBIR federal, state, or local government. Section 10(g) of Public Law 119-83 extends the statutory basis for this pilot, 15 U.S.C. 638(uu), to September 30, 2031.

Phase IIB and other supplements under section 4(b)(6)

Section 4(b)(6) says agencies may offer special awards, such as Phase IIB awards, that supplement or extend Phase II awards, and gives as an example Phase IIB awards that require third-party matching of the SBIR/STTR funds. Three rules follow. Each supplement must be linked to a base Phase II, either the initial or the sequential one. Any SBIR/STTR funds in a supplement are aggregated with the base Phase II to determine the size of that award. And so, while there is no limit on the number of supplements, there is a limit on the total SBIR/STTR funds they can carry: the supplements count toward the initial or sequential Phase II, each of which has a guideline amount of $1 million and a limit of $1.5 million. The directive notes an exception: NIH Phase IIB awards are administered as second, sequential Phase II awards, not supplements, so they are base awards subject to the Phase II guideline and limit on their own.

Those are pre-inflation figures. Section 7(i)(2) says SBA adjusts the guidelines each year and posts the result on SBIR.gov, and the SBIR.gov About page states that as of October 16, 2026 an agency may issue a Phase II award, including modifications, of up to $2,239,578 without SBA approval. Section 7(i)(6) says non-SBIR funds used on an SBIR effort do not count toward the guidelines, which is why matching money from an acquisition program or an investor can push a project's total well past the SBIR ceiling without breaching it. Section 7(h)(1) adds that modifications to increase the dollar amount should be kept to a minimum, except for options in original Phase I or II awards, which is the hook for the Navy's structure below.

How the Navy structures Phase II

The Navy's Phase II page states the sequential rules in Navy terms. A Phase II awardee may receive only one Second (Sequential) Phase II award, which must be within the scope of the original topic, continue the work of the initial Phase II, and have the same guideline amounts and limits as the first, citing 15 U.S.C. 638(ff)(1). A firm with a Phase I from one agency may receive a Subsequent Phase II from a different agency if both make written determinations that the topic is the same, and the subsequent award may be an initial or a sequential one. The page sums up the ceiling: "Awardees may receive a total of two Phase II awards per topic" from the original or another agency. The page says Phase II awards vary in size and duration by Systems Command (SYSCOM).

The structure within a Navy Phase II is a base plus options rather than separate awards. SBIR.gov's agency tutorial on the DoD services describes a Navy Phase II as a base plus up to two options under a cost plus fixed fee contract, says the Navy also uses Subsequent Phase IIs for prototype testing and evaluation "where a cost match is required," and describes a Sequential Phase II as an additional Phase II for the same project from the same SYSCOM. The Navy's fiscal year 2027 Release 1 instructions give the current figures: the maximum Phase II proposal or award amount including all options and TABA is $2,000,000 unless non-SBIR/STTR funding is being added, individual SYSCOMs may award less, the Phase II structure is provided to all Phase I awardees, and, citing directive section 4(b)(5), "there is a limit of one sequential Phase II award per SBC per topic." The Phase I in the same instructions is a $200,000 base with a $115,000 option exercised on selection for Phase II.

The Navy's overview page describes the Commercialization Readiness Program (CRP), formerly the Commercialization Pilot Program, as funded administratively by the statutory 1 percent allocation of SBIR funds to the SYSCOMs "for administering the Phase II.5," the Navy's name for its CRP-backed follow-on, and for non-financial help such as the SBIR/STTR Transition Program.

Air Force: STRATFI and TACFI

The Department of the Air Force runs its Phase II supplements through AFWERX as two funding increases. The AFWERX Phase II transition guide, cleared as AFRL-2026-1324, describes both. A Strategic Funding Increase (STRATFI) adds $3 million to $15 million of SBIR funds to a Phase II for strategic, high-impact capabilities. The matching requirement is one part SBIR funds for every two parts eligible non-SBIR government funding, the 1:2 government-only option, or one part SBIR for one part government and two parts third-party funding, the 1:1:2 government-private option. A firm may execute only one STRATFI in its lifetime. A Tactical Funding Increase (TACFI) adds $375,000 to $2 million at 1:1 matching from government or private sources, with no lifetime limit. Both require an active Phase II with at least 90 days of performance or a Phase II completed within two years, and both require that the Phase II has not already been awarded a second, or sequential, Phase II. The guide's FAQ draws the distinction this post turns on: "A Phase IIb is a modification to the current Phase II contract," while a sequential is a new Phase II contract that increases the scope of the original effort.

The PY26.1 STRATFI Notice of Opportunity, Version 1 of July 2025, says STRATFI provides supplemental funding to eligible Phase II efforts "as a sequential Phase II or Phase IIB modification," with awards from $3 million to $15 million and a period of performance of up to 48 months. Only government organizations may submit the capability package, which must include government or private funding letters for the match.

Army: enhancement, CATALYST, and strategic breakthrough

The Department of War's 2027 SBIR Commercial Solutions Opening preface states the department-wide rule in section 1.10, Phase II Enhancement Policy: certain components developed their own policies under which the component provides a Phase II awardee with additional Phase II SBIR funding if the firm can match the additional SBIR funds with non-SBIR funds from acquisition programs or the private sector. The glossary defines a federally funded award to include "sequential Phase II/subsequent Phase II and cross-agency Phase II."

The Army's How It Works page sets out four Phase II follow-ons. A Phase II runs 12 to 18 months with funding up to $2 million; companies may be invited to submit a proposal for a second Phase II award for further prototype development, testing, and evaluation at the government's discretion, and "may only receive two (2) Phase II awards per topic across all Federal agencies." A Phase II Enhancement is typically executed as a modification to an existing Phase II contract and combines Army SBIR capital with matching funds from an Army transition partner on a 1:1 co-investment model. CATALYST provides up to $8 million in Army SBIR funding matched by an Army customer, up to $3.5 million, and an integrator partner, up to $3.5 million in cash or in kind, for a total of up to $15 million over 36 months. The Strategic Breakthrough award provides up to $30 million in Army SBIR funding with a 1:1 external match, at least 20 percent of it Army customer funding, over up to 48 months. SBIR.gov's agency tutorial records an earlier figure for the enhancement: as of March 2021 the Army could provide up to an additional $550,000.

The strategic breakthrough authority is new law. Section 3 of Public Law 119-83, approved April 13, 2026, adds 15 U.S.C. 638(ff)(3). An agency may award from a strategic breakthrough allocation not more than $30,000,000 to a firm and its affiliates, in a single award or a series tied to production or development milestones, if the total period of performance is not more than 48 months. The firm must have at least one prior Phase II, must demonstrate not less than 100 percent matching from new private capital or new non-SBIR government funding, and must show an effective solution by market research. At DoD, the firm also needs a product at a necessary readiness level with a commitment to a program objective memorandum from an official with the rank of program acquisition executive or higher, and at least 20 percent of the match must be new DoD non-SBIR funding. The agency must complete the award within 90 days of the proposal. Section 3(d) sunsets the authority on September 30, 2031. The Army announced on September 11, 2026 that it had made the first strategic breakthrough award under the law, a $3.5 million co-investment in a magnetic gear drive for tactical vehicles.

NIH and NSF: Phase IIB with matching

NIH's Phase IIB is the case the directive singles out. PA-27-101, the NIH SBIR Phase IIB Strategic Breakthrough Award, was posted May 28, 2026 with a first due date of September 5, 2026 and expires April 6, 2029. Applicants must secure 100 percent third-party matching funds from new private capital, such as another company or a venture capital firm, or new funding from a government agency other than a Phase I or II SBIR or STTR award, or a combination. Total funding may not exceed $30,000,000, with institute-specific limits that vary, some at $3,000,000 and others following SBA guidelines, and the project period may not exceed 4 years. Only a firm that previously received an SBIR or STTR Phase II may apply, one Phase IIB is allowed per project, and the award can only be made after the Phase II has ended. NIH's program basics page describes Phase IIB as being for Phase II projects that need more time and effort than the standard two-year Phase II.

NSF's solicitation NSF 26-511, posted May 22, 2026, treats Phase IIB as a supplement. The Phase II award is up to $1,250,000 over typically 24 months. A Phase IIB supplement of $50,000 to $500,000 lets an awardee build on Phase II results and pair NSF matching funds with investor or customer funds. A TECP supplement of up to 20 percent of the Phase II award pays for research beyond the Phase II objectives, and Phase II awardees may submit Strategic Breakthrough proposals of up to $30,000,000 on a program officer's recommendation. All active Phase II awardees are invited to the supplemental opportunities, subject to available funds.

The mechanisms side by side

How these differ from Phase III

Every mechanism above spends SBIR or STTR funds and therefore lives inside the program's rules: the Phase II guideline and limit, the size and ownership tests at award, and the one-sequential-award rule. Phase III does not. Under 15 U.S.C. 638(e)(4)(C) and section 4(c) of the directive, Phase III derives from, extends, or completes earlier SBIR work and is funded by non-SBIR federal money or private capital, with no limit on the number, duration, type, or dollar value of awards and no application of the small business size limits. The AFWERX transition guide lists Phase III beside STRATFI and TACFI and marks the difference: funding comes from sources other than the SBIR/STTR program, the firm must have an existing Department of the Air Force customer, and the work must derive from, extend, or logically conclude the prior SBIR effort. The Army page says Phase III awards have no statutory caps on dollar value, duration, contract type, or company size and may be made without a new competition. The post on SBIR Phase III covers the derives-from test and the sole-source route in detail.

The practical consequence runs in both directions. Matching money from an acquisition program that funds a Phase II enhancement is non-SBIR money and, under section 7(i)(6), does not count toward the SBIR limit, but the SBIR increase it unlocks does. And a firm that has already taken a sequential Phase II on a project is, by the AFWERX rules, no longer eligible for a STRATFI or TACFI on it, while Phase III remains open at any point.

What to check

• Is the proposed award a new, sequential Phase II under directive 4(b)(5), or a supplement under 4(b)(6) that will be aggregated with the base Phase II against the SBIR.gov ceiling?
• Has the project already received its one sequential Phase II, which the Navy and the Army treat as the last Phase II on that topic and AFWERX treats as closing off STRATFI and TACFI?
• What matching ratio does the component require, from which sources, and is the match in hand at award?
• Does the total SBIR funding on the base Phase II plus all supplements stay within $2,239,578, the ceiling SBIR.gov stated as of October 16, 2026, or does the topic hold an SBA waiver?
• Is the follow-on funded with non-SBIR money, in which case it may be a Phase III with no limits rather than an enhancement with SBIR limits?
• For a strategic breakthrough award, does the firm hold a prior Phase II, a 100 percent match, and at DoD a program objective memorandum commitment and 20 percent DoD non-SBIR funding?

Azcuna's LEDGER turns a trade study into a Decision Package in which every number cites its source and AI agents draft but never decide. It was proposed to the Army under SBIR Phase I topic ARM26BX06-NV012, and the proposal was submitted on October 21, 2026.

Questions people ask

What is a sequential Phase II?

A sequential Phase II is a second Phase II award for the same project. 15 U.S.C. 638(ff)(1) says a firm that receives a Phase II SBIR or STTR award remains eligible to receive 1 additional Phase II award for continued work on that project. Section 4(b)(5) of the SBA Policy Directive says the additional, sequential Phase II has the same guideline amounts and limits as an initial Phase II. The Navy calls it a Second (Sequential) Phase II and requires it to stay within the scope of the original topic.

Can a company get a second Phase II award?

Yes, once per project. Under section 4(b)(5) of the SBA Policy Directive a Phase II awardee may receive one additional, sequential Phase II to continue the initial work. The Navy's Phase II page says awardees may receive a total of two Phase II awards per topic from the original or another agency, and the Army's program page says companies may only receive two Phase II awards per topic across all federal agencies. The Navy's fiscal year 2027 instructions state the limit as one sequential Phase II per firm per topic.

What is a Phase IIB SBIR award?

Phase IIB is an agency label for a supplement or follow-on to a Phase II. Section 4(b)(6) of the SBA Policy Directive gives it as the example of a special award that supplements or extends a Phase II, notes that some agencies require third-party matching for it, and says SBIR funds in such supplements count toward the size of the base Phase II. NIH's Phase IIB Strategic Breakthrough award, PA-27-101, requires 100 percent third-party matching. NSF 26-511 offers a Phase IIB supplement of $50,000 to $500,000 matched by investor or customer funds.

What is a Phase II enhancement?

At the Department of Defense, a Phase II enhancement is additional Phase II SBIR funding a component provides when the firm matches it with non-SBIR funds from an acquisition program or the private sector. Section 1.10 of the Department of War's 2027 SBIR Commercial Solutions Opening states that policy and refers firms to component instructions. The Army describes its Phase II Enhancement as a modification to an existing Phase II contract on a 1:1 co-investment model with an Army transition partner.

How is a sequential Phase II different from a Phase IIB?

A sequential Phase II is a new base Phase II award with its own guideline amount and limit, under section 4(b)(5) of the SBA Policy Directive. A Phase IIB or enhancement under section 4(b)(6) is a supplement linked to a base Phase II, and its SBIR funds are aggregated with that base award to measure its size. AFWERX puts it the same way: a Phase IIB is a modification to the current Phase II contract, and a sequential is a new Phase II contract that increases the scope of the original effort.

What is a Navy SBIR Phase II option?

The Navy structures a Phase II as a base period plus options rather than as separate awards. SBIR.gov's agency tutorial describes a Navy Phase II as a base plus up to two options under a cost plus fixed fee contract. The Navy's fiscal year 2027 Release 1 instructions say the maximum Phase II proposal or award amount including all options and TABA is $2,000,000 unless non-SBIR funding is added, that individual Systems Commands may award less, and that the Phase II structure is provided to all Phase I awardees.

Do Phase II enhancements require matching funds?

Usually. The Department of War's 2027 preface conditions enhancement funding on the firm matching the additional SBIR funds with non-SBIR funds. The Army's Phase II Enhancement uses a 1:1 co-investment model. AFWERX's TACFI requires one dollar of government or private matching for each SBIR dollar, and STRATFI requires either 1:2 government-only or 1:1:2 government and private matching. NIH's Phase IIB requires 100 percent third-party matching. The directive's Commercialization Assistance Pilot in section 4(b)(1)(iii) requires a match equal to the award.

What is the limit on total Phase II SBIR funding?

Section 4(b)(6) of the SBA Policy Directive says there is no limit on the number of supplemental awards but there is a limit on the SBIR funds administered through them, because they count toward the size of the initial or sequential Phase II, each with a guideline of $1 million and a limit of $1.5 million before inflation. SBIR.gov says that as of October 16, 2026 an agency may award up to $2,239,578 in a Phase II without SBA approval. Non-SBIR matching funds do not count under section 7(i)(6).

What is a strategic breakthrough award?

Section 3 of Public Law 119-83, approved April 13, 2026, added it as 15 U.S.C. 638(ff)(3). An agency may award up to $30,000,000 to a firm and its affiliates, in one award or a milestone series, over not more than 48 months. The firm needs a prior Phase II and at least 100 percent matching from new private capital or non-SBIR government funding. At DoD, 20 percent of the match must be new DoD non-SBIR funding, and the firm needs a commitment for inclusion in a program objective memorandum from an official of program acquisition executive rank or higher.

How is a sequential Phase II different from Phase III?

A sequential Phase II is paid with SBIR funds, is subject to the Phase II size and eligibility rules, and may be awarded once per project. A Phase III is paid with non-SBIR funds, derives from, extends, or completes the earlier work, and has no limit on number, duration, type, or dollar value. The AFWERX Phase II transition guide says Phase III needs an existing Department of the Air Force customer and no direct SBIR/STTR funding, while STRATFI and TACFI add SBIR dollars to a Phase II.

Sources

1. 1Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) Program Policy Directive, effective May 3, 2023 · U.S. Small Business Administration, SBIR.gov
2. 2United States Code, 2024 Edition, Title 15, Section 638 - Research and development · U.S. Government Publishing Office
3. 3Public Law 119-83: Small Business Innovation and Economic Security Act · U.S. Government Publishing Office
4. 4About SBIR and STTR · U.S. Small Business Administration, SBIR.gov
5. 5Phase II (Department of the Navy SBIR/STTR Programs) · Department of the Navy SBIR/STTR Programs
6. 6Navy SBIR Overview · Department of the Navy SBIR/STTR Programs
7. 7Department of the Navy SBIR, DoW 2027 SBIR CSO Release 1, Phase I Open Topics Proposal Submission Instructions · Department of the Navy SBIR/STTR Programs, via DSIP
8. 8Department of War SBIR Program, 2027 SBIR Commercial Solutions Opening, Release 1 preface · Department of War SBIR/STTR Program, DSIP
9. 9DOD Services (Individual Agency Requirements tutorial) · U.S. Small Business Administration, SBIR.gov
10. 10SBIR/STTR Phase II Transition: Funding Increase and Post-Phase II Options (AFRL-2026-1324) · AFWERX, Department of the Air Force
11. 11Notice of Opportunity, Department of the Air Force SBIR/STTR Strategic Funding Increase (STRATFI) Program, PY26.1, Version 1, July 2025 · AFWERX, Department of the Air Force
12. 12How It Works (Army SBIR|STTR Program) · U.S. Army SBIR|STTR Program
13. 13Army FUZE Awards Historic $3.5M Strategic Breakthrough to FluxWorks · U.S. Army SBIR|STTR Program
14. 14PA-27-101: NIH Small Business Innovation Research (SBIR) Phase IIB Strategic Breakthrough Award (Parent R44 Clinical Trial Optional) · National Institutes of Health, via Grants.gov
15. 15Understanding SBIR and STTR · National Institutes of Health, Seed
16. 16NSF 26-511: Small Business Innovation Research / Small Business Technology Transfer Phase I, Phase II, and Fast-Track program solicitation · National Science Foundation

Where this shows up in our work

• LEDGER, auditable Army acquisition decisions turns a trade study into a package where every number cites its source and AI drafts but never decides.
• ELLMENT, the offline LLM for E-2D crews answers a crew's question from the aircraft's own manuals and cites the page, with no network.
• TRACE, the offline S1000D and IETM viewer opens S1000D, MIL-STD-3001 and PDF technical manuals on a tablet with every marking intact.