The short answer
Karbon is practice management software built for accounting and bookkeeping firms. It brings email, workflow, client management, a client portal, documents, time, billing, and payments into one product, and it publishes its prices: $59 or $89 per user per month on annual billing, with custom pricing for Enterprise (Karbon pricing). For a firm whose work is recurring client work, such as tax returns, monthly bookkeeping, and payroll, it is a strong fit.
A custom platform is the alternative when your firm's services, structure, or reporting no longer fit a standard practice management model, or when per-user pricing on the plan you need outpaces what the software does for you. This guide covers who Karbon fits, where growing firms start to outgrow it, how the costs compare at different firm sizes, and what to ask before switching. Karbon details come from its own site, checked on October 6, 2026.
Who Karbon fits
Karbon offers three plans, and its own descriptions are a useful guide to fit (Karbon pricing):
- Team, at $59 per user per month on annual billing or $79 monthly, is aimed at small accounting firms and covers the core workflow and collaboration tools.
- Business, at $89 per user per month on annual billing or $99 monthly, adds task automation, automatic client reminders, and industry integrations for growing practices.
- Enterprise, on custom pricing, is aimed at large firms, with unlimited usage limits, customization, and a dedicated Karbon contact.
Every plan includes email triage, team collaboration, workflow, client management, a client portal, document management, and billing and payments. Karbon also connects to many tools accounting firms already use, including QuickBooks Online Accountant, Xero, Gusto, Google Drive, HubSpot, and Ignition (Karbon integrations).
If your team works from shared inboxes, runs the same kinds of jobs every month and every season, and wants templates for that work, Karbon is designed for you.
Where growing firms start to outgrow it
Firms rarely leave Karbon because it does accounting-firm work badly. The pressure usually comes from growth in one of four directions.
Per-user pricing follows headcount. Karbon charges per user, and every team member who needs access is a user. On the Business plan, 25 people cost $2,225 a month on annual billing, and 40 people cost $3,560. Monthly billing costs more per user and is available only to teams of four or more.
Plan limits shape what you can do. Karbon's comparison table sets limits that matter as a firm grows. Team allows three teams and sub-teams, 1,000 contacts, and six months of reporting, with integrations limited to email and the general ledger and no API access. Business raises teams to ten, removes the contact limit, and adds the API, but keeps the six-month reporting period, and custom reporting is a paid add-on on both Business and Enterprise. Firms that need more teams or a longer reporting period move toward Enterprise, which is priced by quote.
Services beyond the accounting workflow. Karbon is built around the accounting firm's core job: recurring work, deadlines, and client requests. If your firm also offers advisory or CFO services, manages wealth, or runs a payroll bureau, check how each would be modeled, and whether any of it would stay in a separate tool.
Reporting partners can act on. Utilization, realization, and work in progress across offices and service lines are the numbers partners manage by. Ask whether they would come from the platform, defined your way, or from a monthly export into a spreadsheet. Our post on utilization tracking that people actually use covers the definitions.
What a custom platform does instead
A custom platform is built around your firm's services and your clients' structure:
- One record per client, with every engagement, contact, document, and invoice attached.
- Intake and engagement in one step: intake forms and engagement letters that create the client and the engagement together.
- Deadlines and workflow per engagement, so busy season and extensions don't live in a spreadsheet. We cover the warning signs in accounting firm workflow beyond spreadsheets.
- Time and billing captured against the right engagement and turned into invoices without re-keying.
- Documents organized per client, with access set by role.
- Partner reporting on utilization, work in progress, and billing across the firm, defined the way your partners use them.
Your tax software, general ledger, and payroll provider stay, connected on Growth and Custom plans. Pricing is per plan, not per seat, so adding a seasonal preparer doesn't change the bill within your plan's limits.
The trade-offs are real. Karbon's email triage, client reminders, and integrations are maintained by a vendor focused entirely on accounting firms. A custom platform is built for one firm, by one team, so ask how it is documented and who maintains it. Our professional services page shows what we typically build for firms.
Karbon pricing vs a custom platform subscription
| Karbon | Localhost Labs | |
|---|---|---|
| Published price | Team $59 and Business $89 per user per month on annual billing ($79 and $99 monthly); Enterprise custom (source) | Starter $497/mo, Growth $1,497/mo, Custom from $2,997/mo |
| How it scales | Per user | Per plan: Starter up to 15 users in one office; Growth up to 50 users across three |
| 10 people | Team $590/mo; Business $890/mo | Starter, $497/mo |
| 25 people | Team $1,475/mo; Business $2,225/mo | Growth, $1,497/mo |
| 40 people | Team $2,360/mo; Business $3,560/mo | Growth, $1,497/mo |
| Billing | Monthly, annual, or multi-year; monthly only for teams of four or more | Month-to-month; optional annual billing saves 10% |
| Data import | Self-service on Team, assisted on Business, fully managed on Enterprise | Migration included on every plan |
Karbon figures use annual billing. At ten people the two are close, and at 25 the Team plan and our Growth plan cost about the same; the gap opens on Business and at larger headcounts. The comparison holds only if the custom platform covers what you use Karbon for, and neither column includes tax preparation software, which stays in place either way.
Questions to ask before switching
- What would our plan cost at next year's headcount? Include seasonal staff, and price the plan you would actually need, not the one you are on.
- Which work templates and automations do we rely on? List them. They are the scope of any replacement.
- How will email fit? If your team works from shared inboxes inside Karbon, ask any replacement exactly how client email will connect to the work.
- What do payments cost? If you collect through Karbon, its pricing page lists 2.6% plus $0.30 for standard cards and 1% plus $0.30 for ACH, capped at $5. Compare like with like.
- When can we switch without risking deadlines? Plan migration and training for a quieter month, not the weeks before a filing deadline.
- How do we get our data out, and in what format? Karbon lists standard data export on Team and Business and custom export on Enterprise. Ask any provider for the details in writing.
The bottom line
Karbon is a well-designed home for accounting firms that run recurring client work, and many firms should stay on it. A custom platform earns its place when your services, structure, or reporting have grown beyond a standard model, or when per-user pricing on the plan you need costs more than a system built around your firm.
To compare the numbers for your firm, start with the software cost calculator or book a 20-minute call.