AI for accountants.
Custom integrations built around your existing data.
Independent CPA firms, small accounting practices, and bookkeeping shops — typically 1–15 staff serving small-business clients across local industries.
What's different about AI for accountants.
Accounting firms sit on more structured client data than almost any vertical: years of GL entries, categorized transactions, tax returns, payroll runs, audit workpapers — all sitting in QuickBooks, Xero, or proprietary tax software. Most of the day-to-day work is pattern-matching that data against rules: is this transaction deductible? Does this client's return follow last year's pattern? Is there a flag in this audit that wasn't there before? AI does this kind of work brilliantly — but only if the data is connected, and only if the assistant knows which rules to apply for which client. Off-the-shelf AI tools can't do that. Custom integrations can.
The busywork patterns most accountants firms run on.
An AI assistant trained on your firm's classification rules can categorize 200+ transactions per minute with the same accuracy as a senior bookkeeper, freeing them for review and exceptions only.
Quarterly check-ins, tax-deadline reminders, missing-document follow-ups — AI drafts them in your firm's tone, you review and send. 30 minutes of work compressed into 5.
Pull last year's workpaper notes, this year's GL deltas, and any flagged items into a one-page summary in seconds, not hours.
Compare this year's draft return against the prior year, flag every meaningful change, suggest reasonable explanations from the books.
New staff asking 'how does our firm handle X?' — answered instantly from a private knowledge base of your SOPs, partner memos, and historical decisions.
A client portal AI that answers 'when is my return due?' or 'what documents do I still owe you?' with real, current data — without your team fielding the call.
Concrete examples, not abstract capabilities.
Read-only sync of client GL data into a private workspace where Claude can answer questions, run categorization, and draft narratives.
Drax, Lacerte, UltraTax, Drake — pull return data and prior-year comparisons into AI workpaper review.
Inbound client docs auto-parsed (1099s, K-1s, brokerage statements), routed to the right return, flagged for missing items.
Karbon, TaxDome, Canopy — natural-language queries on client status across the entire book.
Partner memos, firm SOPs, IRS guidance you actually use — embedded so staff can ask questions in plain English.
Where accountants' data already lives.
- → QuickBooks Online / Desktop
- → Xero
- → Drake / Lacerte / UltraTax / ProConnect
- → Karbon / TaxDome / Canopy (practice management)
- → Email inboxes (client doc submissions)
- → Internal SOPs + partner memos (PDFs, Notion, Google Drive)
Don't see your specific software? It's almost certainly integratable. Bring the list to the discovery call and we'll tell you what's possible.
A specific moment, not a marketing claim.
A staff accountant uploads a client's quarter-end statements and asks the firm's AI: 'compare this to last quarter, flag anything I should ask about.' Two seconds later: a six-bullet list — three are routine, two are worth a call, one is a misclassification the system caught. The accountant calls the client armed with specifics. Time saved: 45 minutes per client per quarter. Across a 200-client book, that's 150 hours per quarter back to billable work.
Build fee + monthly retainer. Both transparent.
Most accounting-firm integrations land in the $1,500–$4,000/mo range depending on data volume. The math works because the time saved (or new clients absorbed at the same headcount) typically pays for the integration in the first month.
We don't mark up API usage. The retainer covers Mainsail's work — building, maintaining, and expanding the integration. You see the actual Anthropic / OpenAI usage in your monthly summary. See the full pricing model →
AI for accountants, plain English.
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How does an AI integration actually save time for accountants?
A staff accountant uploads a client's quarter-end statements and asks the firm's AI: 'compare this to last quarter, flag anything I should ask about.' Two seconds later: a six-bullet list — three are routine, two are worth a call, one is a misclassification the system caught. The accountant calls the client armed with specifics. Time saved: 45 minutes per client per quarter. Across a 200-client book, that's 150 hours per quarter back to billable work.
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What does a Mainsail AI integration cost for accountants?
Most accounting-firm integrations land in the $1,500–$4,000/mo range depending on data volume. The math works because the time saved (or new clients absorbed at the same headcount) typically pays for the integration in the first month. The build fee is one-time; the monthly retainer covers AI API usage (passed through at cost), ongoing maintenance, and new use cases as they come up. No long-term contract — month-to-month after the first month.
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Which accountants software does Mainsail integrate with?
Most of the systems accountants already use have APIs that work cleanly with Claude. Common integrations include: QuickBooks Online / Desktop, Xero, Drake / Lacerte / UltraTax / ProConnect, Karbon / TaxDome / Canopy (practice management), Email inboxes (client doc submissions), Internal SOPs + partner memos (PDFs, Notion, Google Drive). If a tool doesn't have an API but does have data exports (CSV, scheduled reports), we build a slightly different ingestion layer. The only hard 'no' is software that contractually forbids automated access.
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Is my data safe? What stops the AI from being trained on it?
Anthropic's API doesn't train on data submitted via their business tier — it's contractually excluded. Same for OpenAI's enterprise tier. Mainsail builds integrations that route through these enterprise APIs only. Your data is never used to train the underlying model, never shared between accounts, and lives in your authorized workspace only. We document the data flow in the engagement brief so you know exactly what's accessed.
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How fast does the first integration ship?
Discovery call → scoping doc → 2–3 weeks of build → live in your team's hands. Most clients see real time savings within the first month. Compounding wins (the team finds new ways to use the assistant, you add more data sources) typically show up in months 2–4.
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What if I want to start small?
That's how most projects start. Pick the single highest-friction workflow in your business — the thing costing your team the most hours per week — and we build the integration just for that. Usually 2–3 weeks, $1,500–$3,000 one-time, $400–$1,200/mo recurring. If it earns its keep, expand. If it doesn't, you can stop after the first month with no further commitment.
General contractors, mechanical contractors, electrical, plumbing, and specialty trades — typically 5–50 employees running multiple active job sites with crews, subs, and a constant flow of bids, change orders, and invoices.
Independent restaurants, small chains (2–8 locations), and food-service operators — typically running on Toast or Square POS with limited back-office staff and zero appetite for software they have to manage themselves.
Solo agents, small teams (2–10 agents), and boutique brokerages — typically running on a CRM (Follow Up Boss, kvCORE, Wise Agent), MLS access, and a constant flow of leads, listings, and transactions across multiple stages.
Independent property management companies serving 50–500 units of residential or small commercial — typically running on Buildium, AppFolio, or Propertyware with a tenant base, an owner base, and a maintenance crew.
The full service page — what we build, how we price, the process.