How much does it cost to start a business? It's actually impossible to know every cost you'll face, but the more you prepare, the less you will be surprised. We, as small business accounting experts, prepared this guide to help you calculate startup costs.
3 Main Steps to Calculate Startup Costs for Your Small Business
If you're not sure how to calculate startup costs for small businesses, then it's useful to know a three-step process you can follow to get it done. The following actions are how to calculate startup costs for your small business.
1. Do Your Research
The first thing you need to do is make a thorough list of all the expenses you expect to face. After that, you need to estimate the costs involved with every item on the list so you can estimate things accurately. When you do your research, try to look for bargains whenever you can that don't sacrifice the quality you need for what's important.
2. Total Up Everything
There are two things, to sum up here. The first group includes the one-time costs. However, you also need to consider multiple months of the continuing expenses. Your business might not have enough cash flow for all those right away.
3. Breathing Room
When your business is in a growth stage, you should keep anywhere from six months to a whole year of business expenses saved up. Getting fully operational might take longer than you think, so your business might need a cash reserve to fall back on until it can contribute. You might also use these reserves for payroll, inventory, and marketing expenses that grow with your business.
What Does It Actually Cost? Two Examples of Illinois Startups.
Numbers are only meaningful in context. Here's what two common Illinois business types realistically cost to launch and sustain for six months.
Example 1: Boutique Retail Shop in Naperville, IL
An 800-square-foot retail store in Naperville, opening with two part-time employees and a modest product line. Rent is based on $22/square foot annually plus a one-month security deposit.
- IL LLC formation — $150
- Retail space, 6 months rent + security deposit — ~$11,700
- Opening inventory + 5-month replenishment — ~$38,000
- POS system + website — ~$5,400
- Business Owner's Policy, 6 months — ~$1,680
- Grand opening marketing + ongoing social, 6 months — ~$7,800
- 2 part-time employees @ $16/hr, 25 hrs/week, 6 months — ~$31,200
- CPA setup + ongoing bookkeeping, 6 months — ~$3,300
- City of Naperville business license + permits — ~$650
- Utilities, 6 months — ~$2,500
Estimated 6-month total: ~$102,000–$112,000
A modest Naperville retail startup realistically needs $100K–$120K for a solid six-month runway. Being undercapitalized by even 15–20% significantly increases the risk of cash shortfalls in months 3 and 4, before consistent revenue is established.
Example 2: Professional Services Firm (Consulting / Accounting / Law)
A solo practitioner or two-person firm launching from a Naperville co-working space, serving clients across the Chicago suburbs. The owner draws ramps from $5,000 to $10,000/month as client revenue builds.
- IL LLC + attorney review of operating agreement — ~$1,200
- Co-working membership, Naperville, 6 months — ~$2,400
- Professional liability (E&O) insurance, 6 months — ~$1,200
- Website + branding — ~$8,300
- QuickBooks setup + monthly accounting, 6 months — ~$1,100
- Marketing + networking events, 6 months — ~$4,600
- Owner draw, 6 months (ramping) — ~$45,000
- Software subscriptions + tools, 6 months — ~$2,000
Estimated 6-month total: ~$65,000–$75,000
Service businesses generally have lower startup costs, but owner compensation is often the largest single expense. Many Illinois consultants launch with $30K–$50K in capital and increase their draw as client revenue grows. The main risk isn't overhead; it's the gap between your first invoice and your first payment.
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Want a Precise Startup Cost Estimate for Your Illinois Business?
Lewis.cpa's startup advisory team develops tailored cost projections, entity structure recommendations, and cash flow models — so you launch with clarity, not guesswork. We've worked with hundreds of Illinois entrepreneurs from initial concept to their first profitable year.
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Common Business Startup Costs
How much does it cost to start a small business? That will depend on many different business start up costs. Keep in mind that some are one-time fees while others are ongoing expenses. The following are 10 categories you should account for when crunching your numbers.
Incorporation Fees
$150–$500 one-time
Illinois LLC filing runs $150; a Corporation is $175 or more. You'll also pay a $75 annual report fee each year. This is also when you select your tax structure, which is a decision worth reviewing with a CPA before you file.
Insurance
$150–$600/month
At a minimum, plan for a business owner's policy (BOP), general liability, and professional liability. Rates run higher in the Chicago metro. Aim for about 30% more coverage than you think you need and avoid overlapping policies that duplicate costs.
Office or Retail Space
$1,200–$4,500/month
Naperville commercial space averages $18–$28 per square foot annually, while Chicago's Loop reaches $50 or more. Add CAM (Common Area Maintenance) charges on top of base rent—these typically add 20–35% to your monthly cost. Remote and hybrid setups can lower this significantly.
Marketing & Website
$3,000–$20,000 upfront + $500–$3,000/month
Marketing typically accounts for 10–12% of your total first-year budget. A fully developed website can run $15,000 or more. For Illinois businesses, local SEO is especially worth investing in, as most customers in DuPage and Cook counties start with a search.
Equipment & Inventory
$2,000–$80,000+ one-time
This is one of your most variable categories. For example, a consulting firm might need only a laptop and software. On the other hand, a restaurant buildout or retail inventory purchase can run six figures before the doors open. Price this carefully, as it's where startup budgets most often go wrong.
Payroll
20–55% of total business expenses
Illinois minimum wage is $15/hour as of 2025. On top of wages, employers contribute 7.65% in FICA taxes and Illinois unemployment insurance starting at 2.7% for new employers. When building your payroll budget, factor in paid time off, overtime, and any bonuses.
Professional Advisors
$100–$400/hour or $300–$1,500/month on retainer
A CPA, business attorney, and HR consultant are high-value in the early months. Upfront advisory work, including entity setup, tax planning, and contract review, prevents far more expensive problems in the future. Many Lewis CPA clients recover advisory fees through first-year tax savings alone.
Licenses & Permits
$200–$2,500 one-time
Illinois doesn't have a single statewide general business license, but most businesses need city or county permits plus industry-specific licenses. Naperville, Chicago, and surrounding municipalities each have their own requirements. Healthcare, food service, and construction businesses face additional state licensing costs.
Accounting Software
$500–$2,000 setup + $30–$200/month
Software like QuickBooks, Xero, and NetSuite each have different cost and complexity profiles. Our team at Lewis CPA handles full setup and configuration for each platform. When you get this right from day one, you save dozens of hours of cleanup work and make tax season significantly less stressful.
Taxes
Plan for 28%+ of net income
The federal corporate rate is 21%, but planning for 28% or more accounts for Illinois's flat 4.95% personal income tax, the 9.5% corporate income tax rate, and the Personal Property Replacement Tax. Once your business becomes profitable, quarterly estimated payments are required — missing them triggers penalties.
Utilities
$250–$900/month
Start your estimates at $2.75 per square foot per month until you know your actual usage. ComEd and Peoples Gas rates in the Chicago area have climbed in recent years, so energy efficiency measures pay off quickly for businesses with larger footprints.
Startup Mistakes to Avoid in Illinois
Illinois has its own regulatory, tax, and cost factors that catch founders off guard. These are the most expensive mistakes we see at Lewis CPA — every one of them avoidable.
- Choosing the wrong entity structure. Many founders default to an LLC without modeling the tax implications. An S-Corp election can save $5,000–$15,000 per year in self-employment taxes once you're profitable. Getting this right from the start is more important than most people expect.
- Ignoring Illinois-specific taxes. Illinois has a flat 4.95% personal income tax, a 9.5% corporate income tax, and a Personal Property Replacement Tax. Founders who plan based on federal rates alone consistently underprice their services and underestimate what they'll owe.
- Underestimating commercial lease costs. DuPage and Cook County commercial rents run above national averages. Many leases include CAM (Common Area Maintenance) charges that add 20–35% on top of the base rate, which is a significant line item that surprises first-time tenants.
- Skipping payroll tax setup. Illinois requires employer registration, unemployment insurance contributions (starting at 2.7% for new employers), and compliance with the IL Wage Payment and Collection Act. Errors here generate penalties quickly and can draw state audits.
- Delaying sales tax registration. If you sell taxable goods or services, Illinois requires registration under the Retailer's Occupation Tax before your first sale. Late registration can lead to back-taxes plus interest — issues often uncovered early in state audits.
- Mixing personal and business finances. This is the single most common bookkeeping error we correct. It weakens the liability protection of your LLC or Corp and turns tax season into a lengthy reconstruction project.
- Skipping a cash flow forecast. Revenue projections tend to be optimistic; expense projections tend to be incomplete. Without a rolling cash flow model, most founders are caught short in Month 3 — not because the business isn't working, but because timing didn't line up as planned.
Plan Smart, Launch Confidently with Lewis.cpa
Understanding how to calculate startup costs is essential, but turning estimates into an actionable plan requires professional guidance tailored to your business and Illinois’s regulatory environment.
At Lewis.cpa, we don't just run the numbers. We help you structure your business for tax efficiency from day one, stay ahead of the compliance requirements that catch Illinois founders off guard, and build a financial model grounded in reality. Whether you're forming your first LLC, launching a franchise, or scaling a startup that's already gaining traction, reach out to our team.
