FlyFin vs ExactSplit: AI that finds deductions, or a calculation you can check
FlyFin pairs an AI deduction finder with CPA review and filing. ExactSplit is a cited tax engine with reserve tracking and a planning layer. Here is where the two overlap and where they do not.
What FlyFin is
FlyFin positions itself as an AI tax assistant for freelancers. It links your accounts, uses a model to flag deductible expenses, offers CPA review, and files the return. The combination of automated discovery with a human check is its distinctive feature, and for people who want a professional involved without paying full CPA rates, it is a sensible middle ground.
ExactSplit uses a language model in exactly two places, and both are narrow. The classifier asks the model to label merchants against your stated trade, and every verdict it returns is written to a rule table you can override. The bookkeeping assistant lets you ask questions about your own spending, but it is not allowed to do arithmetic. It picks a tested query, the code computes the answer, and the model narrates the result. It is also instructed to refuse advice. Whether you should elect S-corp status is a question it will decline and point at a CPA.
Why we keep the model away from the numbers
A language model asked to total forty transactions will produce a fluent, confident, occasionally wrong figure. For a spending summary that is annoying. For a tax estimate it is dangerous, because the wrong number reads exactly like the right one.
So every number ExactSplit shows comes from deterministic code with automated checks against hand-computed expected values. The self-employment floor, the brackets, the 199A limits, the retirement caps, the mileage rates. The model never touches them. When you ask the assistant what your Bali trip cost, it calls the same query the dashboard uses and reads you the result.
This is a design position rather than a feature comparison, and reasonable products land on different sides of it. We would rather be the product where you can point at any figure and see the rule that produced it.
The estimate itself
The quarterly figure in ExactSplit is not a rate applied to income. It computes self-employment tax with the 92.35 percent base and the 400 dollar floor, federal income tax on the 2026 brackets, the section 199A deduction with the SSTB phase-out and the OBBBA 400 dollar minimum, a flat state rate you set, and then both safe harbor tests. It picks the lower target, subtracts withholding, splits by four, and explains which test won.
Enter last year's total tax and AGI and it handles the 100 versus 110 percent switch at 150,000 dollars of prior year AGI automatically. That switch is the single most common reason a self-employed person underpays without knowing it, and it is easy to get wrong in a product that is built around deduction discovery rather than around the estimate.
Reserve tracking, which nobody else does
The problem with any estimate is that it is a number on a screen. ExactSplit turns it into a per-deposit rate, tells you how much of each incoming payment to move to your reserve account, watches that account's balance, and nets out payments you have made. If the reserve falls more than one quarter behind it says so, before the deadline rather than after.
This is the feature that exists because knowing the number and having the money are different problems. It is not in scope for a filing product, and we have not seen it elsewhere.
Planning, not just reporting
ExactSplit's retirement optimizer solves the circular solo 401(k) employer contribution exactly, respects the shared 415(c) ceiling between a SEP and a solo 401(k), and shows the real saving from one more dollar by re-running the full calculation, so the section 199A clawback is included. At 180,000 dollars of net earnings a maximum deferral saves about 18.8 percent per dollar against a 24 percent bracket. A product that multiplies by your bracket overstates that by a quarter.
The S-corp crossover model subtracts real costs and models the 199A effect in both directions, including the case above the threshold where a sole proprietor with no employees loses the deduction to the wage limitation and an S-corp owner's salary unlocks it. Every result is flagged for a CPA because electing is a structural decision.
Where FlyFin wins
FlyFin files, and it includes human CPA review as part of the product. If you want the return submitted with a professional looking at it and you do not already have a CPA, that is a real advantage. ExactSplit deliberately stops at working papers and a share link for your own CPA, to stay out of the preparer regime.
FlyFin's deduction discovery is also broader by design. If you want a model to be aggressive about finding write-offs, that is what it is built for. ExactSplit's classifier is told to prefer personal when a merchant is ambiguous, because over-claiming is the more expensive error.
We are not quoting prices for either product. They change. Check both sites.
What has been added since
Three additions since this comparison was written are worth knowing about. A safe-to-pay-yourself figure, which turns the tax estimate into a spending answer between deadlines. An accountant view with per-transaction questions and quarterly sign-off, so the numbers you can check are also numbers your accountant has checked. And approved reserve transfers: a suggestion when the reserve is behind, your approval, and confirmation from the feed when the money lands. Nothing is moved on your behalf.
The thread through all three is the one this post is about. Every figure can be inspected, questioned and, now, formally agreed to by the person who signs the return.
The short version
FlyFin: AI finds deductions, a CPA reviews, the return gets filed. ExactSplit: a cited engine computes what you owe, tells you what to set aside from every deposit, tracks that you did, and hands your CPA a finished file. Pick the one that matches the problem you actually have.
Not tax advice. Estimates only. Confirm anything material with a CPA.
Run your number →