NAICS 541211, 541213
Accounting & Tax Preparation Firms in Ontario, CA
The 3 ZIP codes assigned to Ontario contained 29 Accounting establishments in 2023.
- Establishments (2023)
- 29
- 3 ZIP codes
- 10 or more employees
- n/a
- Practical financing floor
- Share of county
- 8%
- San Bernardino County
- City population
- 187,013
- 2025 estimate
Figures cover the ZIP codes the U.S. Postal Service assigns to Ontario (91761, 91762, 91764). ZIP areas are not municipal boundaries: they can extend beyond city limits and are shared between neighbouring places. This is a count of establishments in Ontario's ZIP codes, not a count of businesses inside its city limits.
Establishments by size
Employee-count distribution. For most buyers the businesses worth pursuing sit in the 5 to 49 range: large enough to have a manager and real systems, small enough to be owner-operated.
| Employees | Establishments | Share | Distribution |
|---|---|---|---|
| 1-4 | 20 | 69.0% |
How this market compares
Ontario against every other city in California on the same measure. City figures cover the ZIP codes assigned to the place rather than its municipal boundary, so they are compared as a share of the businesses in those same ZIP codes rather than per resident. Cities with fewer than 500 businesses in total are left unranked.
A far smaller slice of the local business base than the statewide share. Either a genuine gap in provision or a market served from somewhere nearby. Worth checking the neighbouring places below before drawing a conclusion.
- Vs state share
- -48%
- Share of local businesses
- Rank by count
- #83
- of 330 cities
- Rank by share
- #258
- of 287 ranked
- Since 2020
- 0%
- Change in establishments
This compares how much of Ontario’s business base is accounting & tax preparation firms, against the California figure. Base: 5,487 establishments across all industries in the same ZIP codes, 2023. It does not measure revenue, profitability or whether a market is worth entering.
Business size mix
Ontario tracks the California size distribution closely.
| Share of establishments | Ontario | California | Difference |
|---|---|---|---|
| Under 5 employeesOwner-operated, often no management layer | 69.0% | 64.6% | +4.4% |
| 5 to 49 employeesThe range most individual buyers target | 0.0% | 14.2% | -14.2% |
| 10 or more employeesPractical floor for acquisition financing | 0.0% | 4.2% | -4.2% |
Nearest comparable markets
The closest places to Ontario that also have Accounting establishments on record. Useful for spotting a gap next door, or realising the market you are looking at is already served from the town over.
| Market | Establishments | Vs state share |
|---|---|---|
| Chino | 19 | -43% |
| Montclair | 8 | -22% |
| Upland | 41 | +54% |
| Rancho Cucamonga | 50 | -8% |
| Jurupa Valley | 3 | -72% |
The wider San Bernardino County market
Employment and payroll are reported at county level only, so the figures below describe the county Ontario sits in.
- County establishments (2023)
- 371
- San Bernardino County
- County employees
- 1,975
- Mid-March employment
- County annual payroll
- $95M
- All establishments
What acquirers look at
The most acute succession crisis of any professional service category. A large share of partners are past traditional retirement age with no internal successor. Annual recurring compliance revenue with exceptional retention.
Other industries in Ontario
Nearby cities
Sources
- U.S. Census Bureau, 2023 ZIP Code Business Patterns. Establishment counts and size distribution by ZIP code and NAICS, aggregated over the ZIP codes assigned to each city. Retrieved 2026-09-08.
- U.S. Census Bureau, 2023 County Business Patterns. Establishment counts, employment and annual payroll by NAICS. Retrieved 2026-09-08.
- U.S. Bureau of Labor Statistics, Quarterly Census of Employment and Wages (2026Q1). Quarterly establishment counts and employment for employers covered by unemployment insurance. Retrieved 2026-09-08.