For most small business owners, tax preparation is an annual exercise in organised chaos — digging through a year's worth of transactions, matching receipts to expense categories, and hoping the numbers add up. It doesn't have to be that way. With the right system, tax preparation is a natural output of running your books properly throughout the year.
This guide covers everything a small business owner needs to understand about preparing taxes: which expenses are deductible, how to categorise them, estimated tax payments, sales tax obligations, and how to prepare the numbers your accountant needs.
The foundation: keeping your books current
Tax preparation is easy when your books are current. It's a nightmare when you're reconstructing a year's worth of expenses from bank statements in April. The single most important tax preparation practice is maintaining accurate, categorised records throughout the year — not just at year-end.
This means:
- Recording all vendor bills and expenses when they occur
- Reconciling your bank accounts monthly
- Categorising expenses to the right GL accounts so they appear correctly on your income statement
- Keeping invoices and receipts for everything
Understanding Schedule C: the core tax document for sole proprietors
If you operate as a sole proprietor, single-member LLC, or self-employed individual, your business income and expenses flow through IRS Schedule C on your personal tax return. Schedule C has two key sections:
- Part I (Income): Gross receipts minus returns and allowances = net revenue
- Part II (Expenses): 20 specific expense categories where you report deductible business costs
The net profit from Schedule C flows to your Form 1040 and is subject to both income tax and self-employment tax.
IRS Schedule C deductible expense categories
Schedule C Part II lists specific expense lines. Here are the most common for small businesses:
| Line | Category | Examples |
|---|---|---|
| 8 | Advertising | Google Ads, social media advertising, marketing agency fees |
| 9 | Car and truck expenses | Business mileage, gas, vehicle insurance (business portion) |
| 10 | Commissions and fees | Sales commissions, referral fees, agent fees |
| 11 | Contract labor | Payments to contractors, freelancers, 1099 workers |
| 13 | Depreciation | Section 179 deductions, bonus depreciation on equipment |
| 14 | Employee benefit programs | Health insurance, retirement contributions for employees |
| 15 | Insurance (non-health) | Business liability, property, professional indemnity insurance |
| 16 | Interest | Business loan interest, business credit card interest |
| 17 | Legal and professional | Accountant fees, attorney fees, consulting fees |
| 18 | Office expense | Office supplies, postage, printing |
| 20 | Rent or lease | Office rent, equipment leases |
| 21 | Repairs and maintenance | Equipment repair, office maintenance, cleaning |
| 22 | Supplies | Materials consumed in the business, not capitalised |
| 23 | Taxes and licenses | Business license, payroll taxes, excise taxes (not income tax) |
| 24 | Travel | Business flights, hotels, transportation (not commuting) |
| 24b | Meals | Business meals — only 50% is deductible |
| 25 | Utilities | Office electricity, internet, phone (business portion) |
| 26 | Wages | W-2 employee wages and salaries (not owner draws) |
Self-employment tax: the bill most new business owners don't expect
When you work for an employer, they pay half of your Social Security and Medicare taxes (FICA). When you're self-employed, you pay both halves. This is called self-employment (SE) tax, and it's 15.3% of your net profit (technically 15.3% × 92.35%, since you can deduct half your SE tax from your gross income).
For a business with $100,000 in net profit, SE tax is approximately $14,130. This is often a shock to new business owners who focus only on income tax. Building SE tax into your quarterly estimated payment planning is essential.
The good news: you can deduct one half of the SE tax from your gross income when calculating your income tax, and you can deduct 100% of self-employed health insurance premiums.
Quarterly estimated tax payments
Self-employed individuals and business owners are required to pay estimated taxes four times per year rather than once at year-end. The standard IRS deadlines are:
- Q1 (Jan–Mar): Due April 15
- Q2 (Apr–May): Due June 15
- Q3 (Jun–Aug): Due September 15
- Q4 (Sep–Dec): Due January 15 of the following year
Missing estimated payments results in an underpayment penalty, even if you pay the full amount at year-end. A good rule of thumb: pay at least 90% of this year's tax liability, or 100% of last year's (110% if your AGI exceeds $150K), to avoid penalties.
Sales tax: a separate obligation
Sales tax is separate from income tax. If you sell taxable goods or services, you're required to collect sales tax from customers, track it, and remit it to the relevant state taxing authority on a regular schedule (monthly, quarterly, or annually depending on your volume).
Key points:
- Sales tax collected belongs to the government — it's a liability from the moment you collect it
- You must file a sales tax return even in periods with $0 in tax collected (unless you've cancelled your registration)
- State rates, exemptions, and filing schedules vary significantly — consult your state's department of revenue
Using TallyArc for tax preparation
TallyArc's Tax Center is designed to make this process straightforward. The Tax Prep Workbook (under Tax Center → Prep Workbook) automatically:
- Pulls all invoices for the selected tax year and totals gross revenue
- Categorises vendor bills and journal entry expenses into the 18 IRS Schedule C categories
- Calculates net profit, SE tax, and a simplified federal income tax estimate
- Shows sales tax collected vs remitted, with the balance to remit
The Filing Log (Tax Center → Filings & Payments) lets you record every estimated tax payment, sales tax remittance, and annual filing — with a Q1–Q4 deadline calendar to keep you on schedule.
Important: The Tax Center provides planning estimates only. Always review your final return with a licensed CPA or tax professional before filing.