Quick answer: send a clear invoice as soon as the work (or a milestone) is done. Include your name or business name and contact details, the client’s details, a unique invoice number, the invoice date and due date, an itemized list of services with rates and quantities, the total, accepted payment methods and your payment terms (for example, “due within 15 days”). Agree on terms in writing before you start, take a deposit for larger projects, follow up politely on the due date and keep copies for your tax records. In New York, Illinois and California, freelance payment laws also require written contracts and timely payment above certain dollar amounts.
Doing the work is only half of a side hustle. Getting paid, on time and in full, is the other half, and it depends heavily on how you agree on terms and send invoices.
This guide covers what an invoice should include, how to set payment terms, when to ask for deposits, how to follow up on late payments and what some state laws require. It applies to freelancers, service providers and anyone billing clients directly rather than through a marketplace. For the bigger picture of choosing and growing a hustle, see our guide to side hustle ideas.
Sources: New York State Department of Labor, Freelance Isn’t Free Act page and model contract; New York Attorney General, workers’ rights guidance; Illinois Department of Labor, Freelance Worker Protection Act FAQ (820 ILCS 193); California Business and Professions Code Sections 18100-18109 (SB 988, Freelance Worker Protection Act); Internal Revenue Service, Publication 583 (Starting a Business and Keeping Records). General information, not legal advice. Checked October 2026.
Start Before the Invoice: Put Terms in Writing
Most payment problems start before any work is done, when price, scope and timing are left vague. A short written agreement, even an email the client replies “agreed” to, should cover:
- The services or deliverables, itemized.
- The price, and whether it is a flat fee, hourly or per unit.
- When payment is due and how it can be made.
- Any deposit and when it is due.
- What happens if the scope changes.
- Late fees, if you charge them and if they are allowed where you work.
In some states, a written contract is not just smart but required for freelance work. That is covered below.
What to Put on an Invoice
A professional invoice does not need fancy software. It needs complete, accurate information:
| Invoice element | Why it matters |
|---|---|
| Your name or business name, address, email and phone | Shows who is billing and how to reach you |
| Client name and billing address or contact | Makes sure it reaches the right person |
| Unique invoice number | Helps both of you track payments and records |
| Invoice date and due date | Sets clear expectations |
| Itemized services, dates, quantities and rates | Prevents disputes over what was delivered |
| Subtotal, any sales tax and total due | Shows the exact amount owed |
| Payment methods accepted | Makes it easy to pay |
| Payment terms and late fee policy | Reminds the client of what was agreed |
| Purchase order or project reference, if the client uses one | Helps larger clients route approval |
Number invoices in a simple sequence, such as 2026-001, 2026-002, so you never reuse a number. If you sell taxable goods or services, check your state’s sales tax rules and show tax separately.
Choosing Payment Terms
Payment terms tell the client how long they have to pay. Common options include:
- Due on receipt. Common for small, one-time jobs and individual clients.
- Net 7 or Net 15. Due 7 or 15 days after the invoice date; a reasonable middle ground for small businesses.
- Net 30. Standard for many businesses and agencies with accounts payable departments.
- Milestone billing. Invoices at set points in a larger project.
- Retainer. A fixed monthly fee, billed in advance, for ongoing work.
Shorter terms improve cash flow, but larger clients may insist on Net 30 or longer. Know your client’s process before you agree. Ask who approves invoices, whether you need to be set up as a vendor, and whether a purchase order number must appear on the invoice.
Deposits and Upfront Payments
For larger projects, a deposit protects your time and confirms the client is serious. Many freelancers request a portion upfront, with the balance due at completion or at milestones. For custom products, a deposit can also cover materials you buy before starting.
State the deposit in your written agreement, invoice it separately and wait for it to clear before starting work. Be clear about whether it is refundable if the client cancels.
How to Accept Payment
Offer at least two ways to pay so clients have no excuse to delay. Common options include bank transfer, card payments through an invoicing or payment processor, and peer-to-peer apps with business accounts.
Each method has tradeoffs. Card and app payments are convenient but carry processing fees, which are deductible business expenses. Bank transfers are often cheaper but slower to set up. Payments received through apps and card processors may also be reported to the IRS on Form 1099-K once you pass the reporting thresholds, so keep your own records either way.
Using a dedicated separate bank account for your side hustle keeps business payments clean and makes reconciling invoices much easier.
Sending the Invoice
- Send it promptly. Invoice the day the work or milestone is delivered, while the value is fresh.
- Use a clear subject line. For example, “Invoice 2026-014 from [Your Business], due Nov 15.”
- Attach a PDF or send a link from your invoicing tool.
- Send it to the right person. At larger companies, that may be accounts payable rather than your contact.
- Confirm receipt for first-time clients.
Following Up on Late Payments
Late payments happen. A calm, consistent follow-up process usually resolves them:
- A few days before the due date: send a friendly reminder.
- On the due date: confirm the invoice is due today and restate payment options.
- One week late: send a polite note, ask whether there is an issue and resend the invoice.
- Two to three weeks late: call or email the decision-maker, reference your agreement and any late fee terms.
- 30+ days late: send a final written notice with a firm date. Pause further work until the account is current.
Keep every message in writing and keep copies. If a client still refuses, options include small claims court, a collection agency or, in some states, a complaint to the state labor department under freelance protection laws.
Sample Reminder Wording
Short, neutral reminders tend to work best. You can adapt these:
- Before the due date: “Hi [Name], a quick reminder that invoice 2026-014 for [project] is due on [date]. You can pay by [methods]. Thanks again for the work together.”
- On the due date: “Hi [Name], invoice 2026-014 for [amount] is due today. I have attached a copy for convenience. Let me know if anything is needed on your side to process it.”
- One week late: “Hi [Name], I have not yet received payment for invoice 2026-014, which was due on [date]. Could you confirm when it is scheduled? If there is a problem with the invoice, I am happy to correct it.”
- Final notice: “Hi [Name], invoice 2026-014 is now [number] days past due. Per our agreement dated [date], please submit payment by [date]. I will need to pause further work until the balance is settled.”
Handling Disputes and Partial Payments
Sometimes a client pays part of an invoice or questions a line item. Respond quickly, ask exactly what they dispute and refer to the written agreement. If part of the invoice is not in question, ask them to pay that portion now while you resolve the rest.
Record any partial payment against the original invoice number and send an updated statement showing the remaining balance. Under the New York and Illinois laws described below, a hiring party generally cannot require a freelancer to accept less than the contracted amount as a condition of timely payment once work has begun, according to the statutes.
State Freelance Payment Laws
Several states have passed laws protecting independent contractors from nonpayment. They generally require written contracts and payment by a set date.
- New York. The statewide Freelance Isn’t Free Act took effect August 28, 2024. According to the New York State Department of Labor and Attorney General, it covers freelance work worth $800 or more, including work combined over 120 days. Freelancers are entitled to a written contract and payment by the contract date or within 30 days of completing the work if no date is set. The Department of Labor provides a model contract.
- Illinois. The Freelance Worker Protection Act took effect July 1, 2024. The Illinois Department of Labor says it applies to work worth $500 or more over 120 days and requires a written contract listing services, rates, payment method and due date, with payment within 30 days of completion if no date is specified. Complaints can be filed within two years.
- California. The Freelance Worker Protection Act (SB 988), effective January 1, 2025, applies to professional services of $250 or more over 120 days. Hiring parties must provide a written contract with required terms and keep it for at least four years.
Some cities have their own rules as well. If you work in these states, or for clients based there, read the official guidance and use the model contracts where available.
Late Fees
Late fees can encourage prompt payment, but they should be agreed to in advance and written into your contract. Rules on how much interest or fees can be charged vary by state, so check local law before setting an amount. Many freelancers find that a clear due date and steady follow-up work better than fees with small clients.
Invoicing and Your Taxes
Every invoice is part of your income record. IRS Publication 583 explains that you should keep records that support income on your return. Save copies of every invoice, note the date each was paid and match payments to deposits.
Business clients may send you a Form 1099-NEC if they pay you enough during the year, but you must report all income whether or not a form arrives. Our guides to tracking side hustle income and expenses and side hustle taxes for beginners explain how this ties into your return.
Invoicing Tools
You can invoice with a spreadsheet or word processor template, accounting software, payment processors’ built-in invoicing or freelance platforms. Look for features that matter to you: automatic numbering, payment links, reminders, recurring invoices for retainers and reports you can use at tax time. Start simple and upgrade when the volume justifies it.
Common Invoicing Mistakes
- Starting work without written terms.
- Vague line items like “design work” without dates or deliverables.
- Waiting weeks to invoice after the job is done.
- Sending to the wrong contact at a larger company.
- Not following up because it feels awkward.
- Not pricing in time spent chasing payments. Our guide to pricing side hustle services explains how to account for unbillable time.
Frequently Asked Questions
Frequently Asked Questions
What should a side hustle invoice include? Your business details, the client's details, a unique invoice number, invoice and due dates, itemized services with rates, the total, accepted payment methods and payment terms.
When should I send an invoice? Send it as soon as the work or milestone is delivered, or in advance for retainers and deposits.
What does Net 30 mean? The invoice is due 30 days after the invoice date. Net 7 and Net 15 work the same way with shorter windows.
Should I ask for a deposit? For larger or custom projects, a deposit protects your time and materials. Put the amount and refund terms in writing.
What can I do if a client will not pay? Follow up in writing, pause further work and reference your agreement. Next steps can include small claims court, a collection agency or a state labor department complaint where freelance payment laws apply.
Do I need a written contract for freelance work? It is always wise. In New York ($800+), Illinois ($500+) and California ($250+ for professional services), state law generally requires one.
The Bottom Line
Getting paid on time comes down to clear terms, complete invoices and steady follow-up. Agree on scope and payment in writing, invoice promptly, offer easy payment options and keep records of everything. Know whether a state freelance law protects you, and do not be afraid to pause work until a past-due invoice is paid.