For decades, Connecticut has offered a tax credit to reward companies for doing research and development in the state. There was just one problem if you ran a small business: you almost certainly couldn't claim it.
Not because your work didn't qualify. Not because you didn't spend the money. But because of how your business was structured. Connecticut's R&D credit lived entirely inside the corporate income tax — and if you organized as an LLC, an S corporation, or a partnership, you don't file a corporate return. Your tax liability passes through to your personal return instead. No corporate filing, no credit, no matter how much you spent on research.
That changed on May 26, 2026, when Governor Lamont signed Public Act 26-68 into law. For the first time, Connecticut pass-through entities have their own dedicated R&D tax credit, effective for tax years starting January 1, 2026. If you're a small manufacturer tweaking a production process, a biotech startup running early-stage lab work, or a software company building something genuinely new, this is money you may now be eligible to get back.
Why This Gap Existed in the First Place
Connecticut's original R&D tax credit program — still very much in force — gives C corporations two ways to claim a credit against research spending done in the state:
- The Incremental Research Credit: 20% of the increase in Connecticut research expenditures over the prior year, capped at 70% of the corporation's business tax liability.
- The Non-Incremental Research and Development Credit: a tiered rate applied to total (not just incremental) research expenditures, starting at 1% on the first $50 million and stepping up to 6% on amounts above $200 million.
Both of these are genuinely useful credits — if you're a C corporation. But the vast majority of small businesses in Connecticut aren't. They're LLCs, partnerships, and S corporations that elected pass-through tax treatment specifically to avoid double taxation. That's a completely reasonable structural choice, and it happened to leave them locked out of an incentive designed to reward exactly the kind of activity many of them do every day.
As Chris Davis, a vice president at the Connecticut Business and Industry Association, put it while advocating for the fix: "Any time that we don't have this type of incentive for businesses to do this type of activity here, you run the risk of them doing it in a more cost-effective state." For a state whose life sciences sector alone employs more than 24,000 people and contributes an estimated $7 billion to Connecticut's GDP — much of it from small, early-stage companies — that's not an abstract risk. BioCT CEO Jodie Gillon has described Connecticut as "primarily a startup state," where young biotech and life sciences companies need every incentive available to keep their operations in-state rather than relocating somewhere cheaper.
What Public Act 26-68 Actually Provides
The new credit is straightforward on paper, with a few important qualifications baked in.
The credit rate: 6% of qualifying R&D spending paid or incurred during the tax year — the same rate C corporations get on their largest research tiers.
Who qualifies: Your business must be organized as one of the following:
- An S corporation
- An entity treated as a partnership for federal income tax purposes
- A single-member LLC disregarded for tax purposes
You also need gross income under $70 million in your most recent tax year, and the research has to actually happen in Connecticut. Federally deductible research expenses and qualifying basic research payments both count — but only if the work isn't already funded by a government grant or a private contract. If someone else is already paying for the research, you can't also claim a state credit for it.
The caps: Two separate limits apply. Each individual business can claim no more than $1.5 million in credit per year. And the program as a whole is capped at $25 million annually across all participating businesses — so this is a reservation-based system, not an open-ended entitlement.
How you claim it: The Department of Economic and Community Development runs the program through a voucher system. Businesses need to verify their eligible expenses within 90 days after their tax year ends, and the credit is claimed against the reserved voucher amount rather than calculated after the fact on your return. That timing detail matters — if your books aren't clean enough to substantiate R&D spending within that 90-day window, you risk missing the claim entirely.
Refundability — this is the detail most coverage buries: Unlike a lot of state tax credits that only offset liability you already owe, this one is partially refundable, which matters enormously for a startup or early-stage company that isn't profitable yet and has little or no tax liability to offset in the first place.
- Biotechnology companies can get 90% of any excess credit refunded in cash.
- All other qualifying businesses get 65% refunded.
That's a deliberate design choice aimed at exactly the companies who need it most: pre-revenue and early-stage businesses sinking real money into R&D long before they're generating taxable income.
A Worked Example
Numbers make this more concrete than percentages alone. Say you run a small manufacturing company organized as an LLC, with gross income of $8 million last year. During the tax year, you spent $400,000 on qualifying R&D — engineering time spent redesigning a production process, prototype materials, and a contractor brought in to test a new coating formulation. None of that work was funded by an outside grant or contract.
At 6%, that's a $24,000 credit — well under the $1.5 million individual cap, so you'd expect to receive the full amount, assuming the statewide $25 million pool hasn't been exhausted by other applicants in a given year. If your business owes little or no Connecticut income tax because you're reinvesting everything into growth, 65% of that credit — about $15,600 — comes back to you as a refund rather than sitting unused as a credit you can't apply. For a biotechnology company in the same position, the refundable share climbs to 90%, or roughly $21,600 on the same $24,000 credit.
That's real cash, but only if the $400,000 in R&D spending is separable from the rest of the year's expenses when the DECD asks you to verify it.
How Connecticut's Approach Compares
Connecticut isn't the first state to notice that pass-through entities get shut out of research incentives designed around the corporate tax code — several states have added refundable or pass-through-friendly R&D credits in recent years specifically to close this gap. What sets Connecticut's version apart is the combination of a flat, simple 6% rate (no incremental-growth calculation to argue over), a genuinely high partial-refundability rate for non-biotech businesses (65%, with biotech at 90%), and a voucher-reservation system that gives the state a hard ceiling on program cost while still telling individual businesses in advance whether they've secured a spot.
The tradeoff is that $25 million statewide cap. Unlike an uncapped credit that every eligible business can claim in full, this program is first-come, reserved-by-voucher — which means the practical advice for any qualifying business is to apply promptly once your fiscal year closes rather than treating it as a low-priority year-end task. A credit you're eligible for doesn't help if the annual pool is already spoken for by the time you file.
Why Your Bookkeeping Determines Whether You Actually Get Paid
None of this money shows up automatically. To claim the credit, you need to be able to point to specific, substantiated R&D expenses — not a rough estimate, not "some of what we spent on the new product line." Connecticut's own guidance ties qualifying spending to federally deductible research expenses and qualifying basic research payments, which means your books need to separate that spending out clearly, and you need to be ready to verify it within 90 days of your tax year closing.
If your research spending is buried inside a general "operating expenses" account alongside rent, marketing, and payroll, you're going to be reconstructing that breakdown under a deadline — probably by digging through a year's worth of invoices and payroll records rather than pulling a report. Businesses that track R&D-related labor, materials, and contractor costs in dedicated accounts throughout the year, instead of at tax time, are the ones who can actually substantiate a claim when the DECD voucher window opens.
This is also a good moment to note that Connecticut isn't just adding a credit in isolation — Public Act 26-68 also decouples the state from certain federal bonus depreciation changes and delays conformity to some of the federal research expense deduction rules that shifted under recent federal tax legislation. If your business does any R&D at all, your Connecticut return and your federal return may now diverge in ways they didn't before, which is one more reason clean, well-categorized books matter more this year than in years past.
Plain-text accounting, where every transaction lives in a version-controlled, auditable ledger you can query directly, makes this kind of substantiation dramatically easier. Instead of hoping your bookkeeper remembers which invoices were R&D-related eight months later, you can tag research expenses as they happen and pull an exact, defensible total the moment the voucher window opens.
Should You Apply?
If you're a Connecticut LLC, partnership, or S corp with gross income under $70 million doing genuine research and development work in-state — and that work isn't already funded by a grant or contract — this credit is very likely worth pursuing. Even a modest R&D budget can produce a meaningful credit at 6%, and the partial refundability means you don't need to be profitable to benefit.
The practical first step isn't calling a tax attorney — it's making sure your books can already answer the question "how much did we spend on qualifying R&D this year, and can I prove it in 90 days?" If the answer isn't immediate, that's the gap to close before the voucher window opens, not after.
Keep Your Finances Organized from Day One
As Connecticut opens up new tax incentives to more business structures, being able to quickly substantiate exactly what you spent — and on what — is what separates businesses that capture these credits from those that miss the deadline. Beancount.io provides plain-text accounting that gives you complete transparency and control over your financial data, so every R&D dollar is tagged, traceable, and ready the moment you need to prove it. Get started for free and see why developers and finance professionals are switching to plain-text accounting.