Your accountant is preparing the year-end package and asks whether any of your engineering costs qualify for the research and development credit. Your fractional CTO is a large line on the invoice list. Does that fee count?
The short answer: sometimes, partly, and only for the right work. In the US, amounts paid to a contractor for qualified research can count toward the federal research credit, generally at 65 percent of the amount paid, if you bear the financial risk and keep substantial rights to the results. A fractional CTO's time spent directing technical experimentation may qualify. Time spent on hiring, vendor negotiation, board updates, and general strategy usually does not. The difference comes down to what the work was and whether your records can show it. This is not tax advice; it is how I help a founder hand their CPA something usable.
How the credit treats outside help
The federal research credit, under Section 41 of the tax code, is built around qualified research expenses. The main categories are wages for people doing or directly supervising qualified research, supplies used in that research, certain computing costs, and contract research, meaning amounts you pay outside parties to do qualified research on your behalf.
Contract research is generally counted at 65 percent of what you paid, not 100 percent. Two conditions matter a great deal:
- You bear the financial risk. If you pay regardless of whether the work succeeds, that usually points the right way. If payment depends on a successful outcome, the contractor may be the one bearing the risk.
- You keep substantial rights. If the advisor or agency keeps the rights to the work and can reuse it freely, the claim weakens.
The work itself also has to pass the qualified research tests: it must be technological in nature, aimed at a new or improved function, performance, reliability, or quality, involve uncertainty about capability, method, or design at the start, and involve a process of experimentation to resolve that uncertainty.
Which fractional CTO work can qualify
Most of a fractional CTO's month is not research, and pretending otherwise is how claims fail. A realistic split:
Work that can qualify
- Designing and evaluating alternative architectures for a feature where the right approach was genuinely uncertain, such as testing whether a real-time sync design holds up under your load.
- Running and directing technical experiments: prototypes, benchmarks, model evaluations, performance tests, with records of what was tried and what failed.
- Directly supervising engineers doing that experimental work, in the narrow sense of guiding the technical approach.
Work that usually does not qualify
- Hiring, interviewing, and team structure.
- Vendor selection, contract negotiation, and pricing reviews.
- Board decks, investor meetings, and fundraising diligence.
- Routine engineering management, code review of ordinary features, and process changes.
- Work after the product is in commercial production that is maintenance rather than resolving uncertainty.
In a typical early-stage engagement I would expect the qualifying share to be a minority of the time, and in some months close to none. A claim that treats the entire retainer as research is the kind that invites questions.
Why a flat retainer makes this harder
A flat monthly retainer is good for the working relationship, and it is how I price, but it gives your CPA nothing to split. If the invoice says "fractional CTO services, October," the only defensible options are to claim nothing or to reconstruct the split after the fact, which is weak.
The fix is not to switch to hourly. It is to keep a light activity record alongside the retainer. Each month, a short note listing the main technical uncertainties worked on, the experiments run, the result, and a rough share of time by category. That takes perhaps half an hour a month, and it turns an unusable invoice into documentation. What a fractional CTO invoice should show covers the broader point about invoice detail; this is the tax-specific version.
Contract terms that help or hurt
Three terms in the engagement agreement matter for this:
- Ownership of work product. The agreement should say clearly that technical work product, designs, and code created for you belong to you. Without that, the substantial-rights condition is in doubt.
- Payment not contingent on success. A success fee tied to a technical outcome can shift the financial risk to the advisor. If you use one, ask your CPA how it affects the claim.
- Activity records. A line requiring a brief monthly activity summary costs nothing and makes any later claim easier to support.
If the fractional CTO also brings in their own engineers, the same logic applies to that spend, and what you pay when a fractional CTO brings a team is worth reading alongside this.
The startup payroll offset
Most early-stage companies have no income tax to reduce, so a credit sounds useless. For qualified small businesses, generally those with under $5 million in gross receipts for the year and no gross receipts more than five years back, the credit can instead be applied against payroll taxes, up to $500,000 per year for tax years beginning after 2022. It is elected on the return and claimed through Form 8974 with the quarterly payroll filing. That is the reason this matters to a seed-stage founder at all. Your CPA will confirm whether you meet the test. The primary references are the IRS pages for Form 6765, which claims the credit, and Form 8974, which applies it to payroll tax.
Separately, the 2025 tax law restored immediate deduction of domestic research costs under a new Section 174A for tax years beginning after December 31, 2024, replacing the five-year amortization that had applied to domestic research since 2022. That is a deduction question, not the credit, but it uses the same records, so good documentation pays twice.
What to hand your CPA
At year end, give them:
- The engagement agreement, with the ownership and payment terms marked.
- Invoices for the year.
- The monthly activity notes, with the share of time on qualifying work.
- A short list of the main technical projects, the uncertainty in each, and what was tried.
Then let them make the call. My job is to describe the work accurately, not to decide what is claimable.
How I set it up
I bill a flat retainer. When a client is likely to claim the credit, the right move is to keep the monthly activity note from the first month, not reconstruct it in December. My terms are on the pricing page. If you want to talk through how an engagement would be documented, book a call.
FAQ
Can a fractional CTO's fee count toward the R&D tax credit?
Possibly, in part. Amounts paid to a contractor for qualified research generally count at 65 percent, if you bear the financial risk and keep substantial rights to the results. Only the time spent on qualifying technical experimentation counts, not hiring, vendor, or fundraising work.
What share of a fractional CTO's time usually qualifies?
It depends entirely on the work. In early-stage engagements, technical experimentation is usually a minority of the time. A monthly activity record is the only reliable way to know, and your CPA should make the final determination.
Does a flat retainer prevent claiming the credit?
No, but a bare retainer invoice is hard to support. Keep a short monthly note of technical work, experiments, and time split by category so the qualifying share can be shown.
Can a startup with no profit benefit from the research credit?
Possibly. Qualified small businesses can elect to apply the credit against payroll taxes, up to $500,000 per year for tax years beginning after 2022, if they meet the gross receipts tests. Confirm eligibility with a CPA.