The verdict in three sentences
For an accounting firm of 8 to 20 staff in New York, vertical SaaS (Karbon, Canopy, TaxDome) costs $50 to $105 per user per month, a recurring bill that climbs with every hire. A custom build requires $35,000 to $76,000 upfront plus maintenance of $500 to $1,000/month, but it becomes cheaper than SaaS between year 3 and 4. The right call depends on headcount, growth trajectory, and your need for tax, e-filing, and payroll connectors.
What accounting firm software really costs in 2026
The New York market splits into two models. Vertical SaaS bills per user — comfortable at first, heavy for a hiring firm. Custom software demands an upfront investment but freezes the recurring cost.
| Item | Vertical SaaS (20 seats) | Custom (upfront + maint.) |
|---|---|---|
| License / development | $50-105/seat/month | $35,000-76,000 |
| Annual subscription | $12,000-25,200/yr | Maint. $6,000-12,000/yr |
| Tax / e-filing connectors | Included or +$2,200/yr | Included in project |
| Payroll module | +$9-16/paystub | Included or flat fee |
| Initial training | $1,700-4,400 | $3,300-6,600 |
| Data portability | Varies | Total (you own it) |
For 20 seats, the annual subscription gap (up to $25,200) is why the custom question becomes serious beyond 12 staff.
5-year TCO: when custom pays off
Total cost of ownership reveals the true tipping point. We assume a stable 20-seat firm and a median subscription of $77/seat/month.
| Horizon | SaaS cumulative | Custom cumulative | Gap |
|---|---|---|---|
| Year 1 | $18,480 | $55,000 (dev + maint.) | +$36,520 |
| Year 2 | $36,960 | $63,000 | +$26,040 |
| Year 3 | $55,440 | $71,000 | +$15,560 |
| Year 4 | $73,920 | $79,000 | +$5,080 |
| Year 5 | $92,400 | $87,000 | -$5,400 |
Break-even lands at late year 4 / early year 5 (2026 order of magnitude, assuming 20 seats and $46,000 dev). Below 12 seats, SaaS almost always wins; beyond 25 seats, custom wins from year 3.
Mini case study
Philip, partner at an 18-person firm in New York, pays $85/seat/month, or $18,360/year. His team loses 7 hours per week per staffer on rekeying and manual reconciliation. A custom tool at $50,000 + $770/month maintenance automates ledger imports and reconciliation: an estimated 6 hours/week/staffer saved, roughly 108 hours/week firm-wide. Valued at a $40 hourly cost, those hours represent nearly $225,000/year of recovered capacity — the build pays for itself in productivity within the first tax season.
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FAQ
Does custom include tax and e-filing connectors?
Yes, they are in the project scope. Budget $4,500 to $8,800 of dedicated development for tax, e-filing, and payroll interfaces, usually inside the $35,000-76,000 range.
How long to deliver a custom tool?
Standard 2026 timeline is 10 to 16 weeks depending on scope (matters, billing, auto-reconciliation, client portal). A working MVP can ship in 8 weeks.
What happens to my SaaS bill as I grow?
It scales linearly: each new hire adds $600 to $1,260/year. That marginal cost is exactly what makes custom attractive for growing firms.
What maintenance should I plan for?
Maintenance of $500 to $1,000/month covers fixes, regulatory updates (tax forms, e-filing formats), and support. It is essential for compliance.
Can I recover my data if I switch?
With custom, you own the database and code: full portability. With SaaS, check export terms before signing — it is a key negotiation point.
Let's scope your project. Tell us your headcount, priority connectors (tax, e-filing, payroll), and target budget, and we will price SaaS vs custom side by side. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
