A net profit tax is a local tax that cities and counties impose on the earnings of businesses and self-employed people operating within their borders, calculated on profit after expenses rather than total revenue. Rates commonly fall between 1% and 3% of net business income, and the obligation depends entirely on where you do business. Confusing it with a gross receipts tax is one of the most common and costly mistakes business owners make.
Who Owes the Tax
The tax generally applies to sole proprietors, partnerships, and unincorporated associations earning income within a municipality that levies it. Some jurisdictions also tax S-corporations and C-corporations, though corporations often fall under a separate local business income tax or corporate net income tax. Which entities are covered depends on your municipality’s tax code, so a quick call to the local revenue department beats an assumption.
If you live in a city that imposes the tax, you typically owe on all your business income regardless of where you earned it. Non-residents pay only on profits tied to work performed or services delivered inside the city limits. That taxable connection, often called nexus, can be triggered by maintaining an office, storing inventory, or regularly providing services in the jurisdiction. Even occasional work inside city boundaries can create nexus in some municipalities, so the threshold is lower than many owners expect.
Net Profit Tax vs. Gross Receipts Tax
These two taxes sound alike and work very differently. A net profit tax lets you subtract business expenses before calculating what you owe. If your business brought in $200,000 but spent $150,000 on rent, payroll, and supplies, you pay tax on the $50,000 profit. A gross receipts tax applies to your total revenue with no deductions, so under the same numbers you’d owe on the full $200,000.
The gap widens for thin-margin businesses. A restaurant earning $500,000 in revenue but keeping only $30,000 in profit pays net profit tax on $30,000. Under a gross receipts tax, that same restaurant owes on the full half million. Knowing which type your municipality uses determines how you calculate what you owe and which deductions apply.
Calculating Your Taxable Net Profit
The calculation starts with gross receipts, meaning total revenue before any subtraction. From there, deduct allowable business expenses to arrive at net profit. Most municipalities align their deduction rules closely with the IRS, so if your federal return is done, much of the work is already done too.
Common deductible expenses include cost of goods sold, rent for business space, utilities, employee wages, insurance premiums, and supplies. These need to be ordinary and necessary for running the business. Personal expenses and capital purchases that must be depreciated over time don’t count as current-year deductions. Some municipalities disallow certain deductions the IRS permits, such as taxes paid to other local jurisdictions or specific types of interest income, so local rules deserve a read.
If expenses exceed revenue, the result is a net loss and no tax is owed for that period. Most municipalities still require you to file a return showing the loss. Some jurisdictions allow you to carry the loss forward to offset profits in future years, though carryforward periods and rules vary. Filing on time, even at zero, protects you from penalties and keeps your account in good standing.
Registering With Your Local Tax Authority
Before you can file, most municipalities require a business tax account. This is separate from registering your business with the state or obtaining a federal Employer Identification Number, and new owners often overlook it. Registration typically asks for your legal business name, business structure, federal tax ID or Social Security number, the date you started operating in the jurisdiction, and a description of your activities.
Many cities offer online registration portals that process applications within a few business days. Registration is often free, though some jurisdictions charge a small administrative fee. Once registered, you’ll receive a local tax account number used on all future filings. If you’ve been operating without registering, most municipalities allow late registration but may assess penalties or interest on tax that should have been paid during the unregistered period.
Pulling the Numbers From Your Federal Return
Your federal return provides the foundation for the local filing. Sole proprietors need Schedule C (Form 1040), which reports profit or loss from a business. Line 1 shows gross receipts or sales, and Line 31 shows net profit or loss after all deductions. Those two numbers are typically what the local form asks for first.1Internal Revenue Service. 2025 Instructions for Schedule C (Form 1040)
Partners in a partnership use Schedule K-1 (Form 1065), which reports each partner’s share of the partnership’s income, deductions, and credits. Your share of partnership income flows through to your personal return, and that same figure is what most municipalities use to calculate the local obligation.2Internal Revenue Service. Partner’s Instructions for Schedule K-1 (Form 1065) (2025)
When moving data from federal forms to the local return, accuracy beats speed. Discrepancies are easy for revenue departments to spot and can trigger an audit or administrative review. Double-check that gross receipts and net profit match exactly unless your municipality requires specific adjustments.
Apportioning Income Across Jurisdictions
If your business operates in more than one taxing jurisdiction, you won’t owe the full tax to every city where you have a presence. Instead, you apportion income using a formula that reflects how much of your activity actually occurs in each place. The most common approach uses three factors: the percentage of your total property located in the jurisdiction, the percentage of your total payroll paid there, and the percentage of your total sales made there.
If 40% of your payroll, 30% of your property, and 50% of your sales are in a particular city, you average those percentages to find the share of net profit taxable there. Some municipalities weight the sales factor more heavily or use only one or two factors, so the exact formula depends on local rules. The local form usually includes a worksheet that specifies which factors apply and how to weight them.
Estimated Quarterly Payments
Many municipalities require estimated payments throughout the year rather than one payment at filing time. It works much like the federal estimated tax system, with quarterly installments smoothing the government’s revenue and your cash flow.
The federal threshold for estimated payments applies when you expect to owe $1,000 or more after subtracting withholding and credits. Local thresholds vary and are often lower. Federal quarterly due dates fall on April 15, June 15, September 15, and January 15 of the following year, and many municipalities follow the same schedule.3Internal Revenue Service. Estimated Tax for Individuals (Form 1040-ES) Your local revenue department’s website will show the dates and dollar thresholds that apply in your jurisdiction.
Underpaying can trigger penalty charges even if you pay the full balance at filing. Federally, you avoid the underpayment penalty by paying at least 90% of the current year’s tax or 100% of the prior year’s tax (110% if your adjusted gross income exceeded $150,000). Many local jurisdictions follow a similar safe harbor structure, though specific percentages may differ.
Filing and Payment
Most returns are due on April 15 or shortly after the federal deadline, though some municipalities set their own dates. If the due date falls on a weekend or holiday, the deadline typically shifts to the next business day. Filing extensions are available in many jurisdictions, but an extension to file is almost never an extension to pay. Interest still accrues on any unpaid balance from the original due date.
Many municipalities offer online portals for filing and paying in the same session. Electronic filing is generally faster and produces an immediate confirmation number that serves as proof of compliance. Paper returns are still accepted in most places, but processing takes longer, and certified mail is worth using for the delivery record.
Payment options typically include electronic bank transfers, credit cards, and paper checks. Credit card payments often carry a convenience fee of 2% to 3% of the payment amount, which adds up on larger balances. Electronic bank transfers are usually free or close to it.
Deducting the Tax on Your Federal Return
Local net profit taxes paid on business income are generally deductible on your federal return. Under federal law, state and local income taxes paid in carrying on a trade or business are allowed as a deduction.4Office of the Law Revision Counsel. 26 USC 164 – Taxes Sole proprietors take the deduction on Schedule C as a business expense, reducing federal taxable income. Partners and S-corporation shareholders may deduct their share of local taxes paid through the business on their individual returns.
This deduction is separate from the $10,000 cap on state and local tax deductions that applies to personal itemized deductions. Business-related state and local taxes are deducted on the business return and are not subject to that cap, a benefit many self-employed taxpayers miss.
Penalties for Late Filing or Underpayment
Filing late or underpaying triggers penalties and interest that compound over time. Specific amounts vary by municipality, but most jurisdictions charge a percentage-based penalty on the unpaid balance for each month the return is overdue, plus interest that accrues from the original due date. Some cities also impose flat-dollar penalties for failure to file, even when no tax is owed.
Ignoring the obligation entirely is where the numbers get large. Municipalities that discover unregistered or unfiled businesses often assess back taxes for multiple years along with accumulated penalties and interest, and the total can dwarf the original tax. If you’ve fallen behind, filing voluntarily before the municipality contacts you typically produces reduced penalties compared to waiting until enforcement begins.