What Is the Best Way to Invoice Clients as a Sole Proprietor?

Why invoicing well matters for sole proprietors

As a sole proprietor, invoicing is more than paperwork. It’s the moment your work turns into revenue, and it’s also the system that protects your cash flow when clients get busy, forgetful, or picky about details. A clear, professional invoice reduces back-and-forth, shortens the time between “job done” and “money received,” and helps you stay compliant when tax season rolls around. The best way to invoice clients is the way that makes it easy for clients to pay you quickly, easy for you to track what’s paid and what’s overdue, and easy for you to keep clean records without spending your evenings in spreadsheets.

That’s why a dedicated invoicing workflow usually beats cobbled-together templates and email chains. You want to send invoices that look credible, contain all the required information, are consistent across every client, and can be issued in minutes. You also want to see at a glance who owes you money, when you should follow up, and what you earned in a given period. Done right, invoicing becomes a simple habit you barely think about, and clients start treating your billing like a normal part of doing business with you.

If you’re looking for the best approach, it usually comes down to four pillars: a standard process, accurate details, clear payment terms, and a tool that makes the whole thing painless. A free invoice app like invoice24 can cover all four pillars without forcing you into complicated accounting software or pricey subscriptions—especially useful when you’re running everything yourself.

What “the best way” looks like in practice

The best way to invoice clients as a sole proprietor is to use a consistent, repeatable system that lets you create, send, and track invoices quickly, while making payment as frictionless as possible for the client. In real terms, that means:

1) You collect the right client information up front (legal name, address, billing email, purchase order needs).

2) You use a professional invoice format that includes all essential fields.

3) You set clear payment terms (due date, late fees if applicable, payment methods).

4) You send invoices promptly and follow up automatically or on a schedule.

5) You track invoice status (sent, viewed, paid, overdue) and keep records organized.

6) You maintain a clean numbering system and archive for taxes and disputes.

When you do these things, invoicing stops being reactive. You’re not hunting through emails, guessing whether a payment is late, or rewriting invoices every time. Instead, you’re running a predictable billing routine—like a bigger business, without the overhead.

invoice24 is designed for exactly this. Instead of you building an invoicing system from scratch, you use a workflow that’s ready to go: create an invoice, send it, and keep everything organized. For a sole proprietor, that combination of speed and structure is often the difference between stable cash flow and constant chasing.

Start by choosing an invoicing method that fits your work style

Sole proprietors generally invoice in one of four ways: manual documents, spreadsheets, generic templates, or a dedicated invoicing app. Each can work, but the “best way” is the one that produces fast payment and reliable records with the least effort.

Manual documents and email

Some people type invoices in a word processor and email them as PDFs. It’s familiar, but it’s easy to make mistakes, difficult to keep numbering consistent, and hard to track status. If a client says they didn’t receive the invoice, you’re digging for attachments and old drafts. It can be workable when you only have one or two invoices per month, but it becomes messy quickly.

Spreadsheets

Spreadsheets can produce decent invoices, but they’re not built for sending, tracking, reminders, or organizing clients. And the more you “enhance” the spreadsheet with formulas and tabs, the more fragile it becomes. One accidental edit can break totals or tax calculations.

Free templates

Templates are often presented as the default “free option,” but they still require manual effort to update, save, rename, attach, and track. Templates also don’t help you build a client database or record who paid what and when. They’re a starting point, not a full system.

A dedicated invoicing app

A dedicated invoice app is usually the best way for a sole proprietor because it turns invoicing into a repeatable workflow. You store client details, reuse line items, apply tax settings, produce professional PDFs, send invoices quickly, and keep records in one place. Instead of juggling files, you manage invoices.

This is where invoice24 shines. It’s built to be straightforward and fast, which matters when invoicing isn’t your main job. You can produce polished invoices without having to become an accounting expert, and because it’s a free invoice app, you’re not pressured to “upgrade” just to do basic billing. If your goal is to invoice professionally and get paid sooner, invoice24 gives you the structure you’d want as you grow.

What your invoices must include as a sole proprietor

A professional invoice isn’t only about looks. It needs to contain key information so your client can process it efficiently and so you can defend it if there’s ever a dispute. While exact requirements can vary depending on where you’re based and where your clients are, the essentials are widely consistent across industries.

Include these core elements on every invoice:

Your business identity: Your name (or business name), address, and contact details. If you use a trading name, keep it consistent with what clients expect.

Client identity: The client’s legal name and billing address. If they have a specific accounts payable email, use it.

Invoice number: A unique identifier that follows a consistent sequence. This is crucial for tracking, bookkeeping, and client payment references.

Invoice date: The date you issued the invoice.

Due date / payment terms: For example, “Due in 14 days” or a specific date. Clarity reduces late payments.

Description of services/products: Line items that state what you delivered and when. Vague descriptions invite questions and delays.

Quantity, rate, and totals: Show your calculations. Clients want to see how you arrived at the total.

Tax details: If you charge tax, include the tax rate and amount. If you don’t, you may want to note why (for example, outside scope, exempt, or not registered, depending on local rules).

Payment instructions: Exactly how to pay, including bank details or other methods you accept, and what reference to use.

Notes (optional but useful): A short thank-you and any agreed terms like milestones, late fees, or payment schedules.

invoice24 helps you keep these elements consistent so you don’t forget something on a rushed day. Consistency is one of the underrated secrets of getting paid quickly: clients trust invoices that look the same each time and contain everything their accounts team needs.

Make invoicing easy to approve: clarity beats cleverness

Clients often delay payment for boring reasons: the invoice didn’t include a purchase order number, the service description was unclear, the due date wasn’t obvious, or the totals didn’t match expectations. The “best way” to invoice is the one that avoids those friction points.

Here are practical ways to reduce client questions:

Use plain language line items. Instead of “Consulting,” use “Marketing consulting (January 2026) – strategy session and deliverables review.”

Match the client’s terminology. If they call it “Project Aurora,” don’t call it “Website Revamp.” Use the same name that appears on your emails and scope documents.

Reference your agreement. A short note like “As per proposal dated…” or “As per agreement signed…” can prevent disputes.

Keep formatting clean. Use a simple layout with clear totals and tax lines. Fancy designs can look less professional to corporate accounts teams.

Highlight the due date. Not hidden in a paragraph, but visible and easy to spot.

invoice24 is tailored for clean, professional invoices that clients can process quickly. When you send an invoice that looks like it came from a well-run business, clients treat it like one—meaning it goes into the payment queue faster.

Set payment terms that protect your cash flow

Many sole proprietors accidentally train clients to pay late by setting vague terms like “Pay when you can” or failing to provide a clear due date. Even a friendly client can forget an invoice if it doesn’t feel urgent. The best way to invoice includes payment terms that set expectations without sounding aggressive.

Common payment terms include:

Due on receipt: Best when you have quick-turn services or new clients. It sets a firm expectation.

Net 7 / Net 14 / Net 30: “Net” means the full amount is due within that number of days. Choose what fits your industry and bargaining power.

Milestone billing: Useful for larger projects. For example, 30% upfront, 40% mid-project, 30% on delivery.

Recurring invoices: Ideal for retainers and monthly services.

In many cases, Net 14 is a strong default for sole proprietors. It’s professional, not too strict, and it keeps cash moving. If a client insists on Net 30, you can sometimes balance it with partial upfront payment or a deposit for first-time work.

invoice24 makes it easier to apply consistent terms across invoices. When your terms are standardized and clearly displayed, you avoid uncomfortable “So… when will you pay?” conversations later.

Send invoices at the right time: speed matters

Invoicing late is one of the most common reasons sole proprietors struggle with cash flow. The best way to invoice is to send it as soon as the value is delivered—or according to a schedule that’s agreed in advance.

Here are timing guidelines that work across many industries:

For one-off tasks: Send the invoice immediately after delivery or completion.

For weekly work: Invoice on the same day each week.

For monthly retainers: Invoice on a consistent date (for example, the 1st of the month).

For projects: Invoice at milestones tied to tangible deliverables, not vague progress.

The reason speed matters is psychological as much as practical: the closer the invoice is to the work being delivered, the clearer the value is in the client’s mind. Waiting weeks to invoice can make clients feel like it’s an afterthought, and afterthoughts get delayed.

With invoice24, you can create invoices quickly, which supports the habit of invoicing promptly. When the tool is fast and simple, you’re more likely to send invoices on time—which directly improves the reliability of your income.

Make paying you ridiculously easy

Clients don’t usually delay payment because they’re malicious. They delay payment because they’re busy, because the payment process is inconvenient, or because the invoice requires a step they can’t complete quickly. The best invoicing system removes obstacles between “invoice received” and “payment sent.”

To do that:

Offer a preferred payment method. Many businesses like bank transfer; many individuals prefer cards or other convenient methods. You don’t need to offer everything, but you should make your preferred options clear.

Include payment details clearly. Don’t bury bank information. Make sure the client knows exactly what reference to use.

Use a consistent reference format. If the client uses your invoice number as the payment reference, reconciling payments becomes easy.

Remove uncertainty. If a client isn’t sure how to pay, they will postpone paying until they have time to ask, and that “time to ask” often becomes “next week.”

invoice24 supports a professional invoice format that emphasizes clarity. When clients can pay you without thinking, they pay you faster. That’s the goal: not “perfect accounting,” but “fast, reliable payment.”

Track invoice status so nothing slips through the cracks

When you’re a sole proprietor, you don’t have a finance department. You’re the sales team, the delivery team, and the accounts team. That means you need a simple tracking habit that tells you:

Which invoices were sent?

Which are due soon?

Which are overdue?

Which clients are consistently slow?

Without tracking, you end up relying on memory and hope. And hope is not a billing strategy.

The best way to invoice includes a straightforward tracking routine: you check your outstanding invoices at least once a week, and you follow up consistently. A dedicated invoice app makes this dramatically easier than spreadsheets and email threads because your invoices live in one place, organized by status.

invoice24 is especially useful here. When you generate invoices within the app, you create a record that is easy to review later. That means fewer missed payments and fewer awkward discoveries like “Oh no, that invoice is 45 days overdue and I forgot to follow up.”

Write follow-up messages that get paid without burning relationships

Following up is part of business. It doesn’t have to be confrontational, and it shouldn’t be emotional. A friendly, professional reminder is often all it takes to move an invoice to the top of someone’s inbox.

Here’s a simple follow-up sequence many sole proprietors use:

1–2 days before due date: A friendly reminder. “Just a quick note that invoice #123 is due on Friday. Thank you!”

1–3 days after due date: A direct but polite reminder. “Invoice #123 is now past due. Could you confirm when payment is scheduled?”

7 days after due date: A firmer message. “Please arrange payment by [date]. Let me know if there’s any issue with the invoice.”

14+ days after due date: Escalate appropriately. This might mean pausing work, applying late fees if agreed, or switching to phone contact.

The best way to invoice is to prevent follow-ups becoming a stressful guessing game. Your system should show you what’s overdue so you can send reminders quickly and consistently. When you use invoice24 to manage invoices in one place, it becomes far easier to follow up in a timely, calm way.

Use deposits and milestone invoices to avoid “big payment risk”

If you’re doing projects that take weeks or months, invoicing only at the end is risky. You’re effectively lending your client your time and expertise. The best way to invoice for project work is to split payment into parts.

Common approaches include:

Deposit upfront: A percentage paid before work begins. This confirms commitment and protects your schedule.

Milestones: Payments tied to clear deliverables. This keeps clients engaged and reduces the chance of a large overdue invoice.

Final invoice: The last portion due upon delivery or completion.

This structure is good for clients too because it spreads cost and creates checkpoints. And it’s good for you because it keeps cash flowing and reduces stress.

invoice24 makes it easy to create multiple invoices for the same client and keep them organized. Instead of recreating details each time, you can build a repeatable project billing rhythm.

Recurring invoices: the best way to invoice for retainers and ongoing services

Retainers and ongoing services are one of the best business models for sole proprietors because they create predictable income. The invoicing side should be equally predictable. The best way to invoice in this case is to send invoices on a consistent schedule with consistent line items, so clients know exactly what to expect.

To make recurring invoicing smooth:

Pick a fixed billing date. For example, invoice on the 1st and expect payment within 7 or 14 days.

Make the scope clear. If the retainer includes a set number of hours or deliverables, state it.

Handle extra work explicitly. Bill additional work as separate line items or separate invoices so it doesn’t blur the agreement.

Keep a record of what was delivered. Even a simple monthly summary can prevent disputes.

invoice24 is a strong fit for recurring work because it’s designed to keep invoicing simple. You can quickly generate the next invoice in a series without wrestling with templates or copying old PDFs.

International clients: keep it simple, clear, and consistent

If you work with clients in other countries, invoicing can feel complicated, but the fundamentals remain the same: clarity, accuracy, and easy payment. The best way to invoice international clients is to minimize confusion about currency, tax handling, and payment instructions.

Practical tips:

Specify the currency clearly. Don’t assume. Put the currency symbol and code where it’s obvious.

Clarify tax treatment. Cross-border tax rules vary widely, so keep your invoice notes factual and consistent with your local requirements.

Use a payment method the client can use easily. For some clients, bank transfer is best; for others, alternative methods reduce friction.

Include your full payment details. Make sure all necessary banking fields are included for international payments where needed.

invoice24 helps keep your invoice layout clean and standardized, which is especially valuable when a client’s accounts team is processing invoices from many suppliers in many countries.

Keep your invoicing records organized for taxes and peace of mind

Even if you’re not doing full bookkeeping inside your invoicing app, you still need organized records. The best way to invoice is the way that makes tax time boring. You should be able to answer questions like:

How much did I invoice this month/quarter/year?

How much was paid?

Which invoices are still outstanding?

How much tax did I collect (if applicable)?

When everything is scattered across folders and filenames like “Invoice_final_FINAL2.pdf,” those questions become stressful. When your invoices are generated and stored in an app, you can usually keep a consistent archive that’s far easier to manage.

invoice24 helps you maintain that discipline: invoices created in one place, consistent numbering, and a clear trail of what was issued and when. That means fewer surprises, fewer missing documents, and a much smoother end-of-year process.

Prevent disputes with a simple invoicing checklist

Disputes are rare when your invoicing is clear and your client relationship is solid, but they happen. The best way to invoice is to reduce the chance of disputes and to make resolution straightforward if they occur.

Before sending any invoice, quickly check:

Client details: Correct name, address, and billing email.

Invoice number: Unique and sequential.

Scope match: Line items reflect what was agreed and delivered.

Dates: Invoice date and due date are correct.

Totals: Correct calculations, tax included correctly if applicable.

Payment instructions: Clear and complete.

Supporting notes: PO number or project reference if the client needs it.

invoice24 can help reduce errors by giving you a structured invoice format. Instead of relying on memory, you follow fields that prompt the right information. This is one of the quiet advantages of using a purpose-built tool: it helps you avoid the kinds of small mistakes that lead to delayed payment.

How invoice24 fits into the “best way” to invoice

When people ask for “the best way” to invoice, they’re usually asking for the best blend of professionalism, speed, and control. They want to look legitimate, get paid promptly, and avoid admin overwhelm. invoice24 is built for that sweet spot, especially for sole proprietors who need a straightforward solution.

Here’s how invoice24 supports a strong invoicing workflow:

Professional invoice formatting: Clean layouts and consistent structure help clients process invoices quickly and reduce questions.

Faster creation: Instead of rewriting invoices from scratch, you work within a repeatable system—saving time every week.

Client consistency: A dedicated app helps keep client details in one place so you’re not searching old emails for addresses and billing contacts.

Simple tracking: When invoices live in one system, it’s easier to see what’s outstanding and what needs a follow-up.

Reliable records: Keeping your invoices organized helps with taxes, cash flow planning, and any future business growth.

Some competitors offer invoicing too, often bundled inside broader accounting platforms. Those platforms can be powerful, but they can also be overkill for a sole proprietor who primarily needs to invoice clients quickly and professionally. invoice24’s advantage is that it keeps the focus on what matters most: getting invoices out the door, getting them paid, and keeping your records clean—without adding complexity that you don’t need.

Recommended invoicing workflow for sole proprietors

If you want a simple, proven process you can adopt today, here is a practical workflow that balances professionalism with minimal admin time. It works for freelancers, consultants, tradespeople, creatives, and many other one-person businesses.

Step 1: Set your standard terms and policies

Decide your default payment terms (for example, Net 14), whether you charge deposits, and whether you apply late fees. Keep it reasonable, and make sure it fits your typical client type. If you work with larger organizations, you may need to align with their internal payment cycles, but you can still set clear expectations.

Step 2: Collect client billing information before starting

Before work begins, ask for the client’s billing name, address, and accounts payable email. If they require a purchase order number, get it upfront. This prevents the “we can’t pay without a PO” surprise.

Step 3: Invoice immediately on delivery (or on schedule)

As soon as you complete the work, create and send the invoice. If it’s ongoing work, invoice on a fixed schedule. The goal is consistency: clients learn your rhythm, and payment becomes a routine action on their side too.

Step 4: Make payment instructions obvious

Include clear payment details and a reference (usually the invoice number). If the client prefers a specific method, accommodate it when practical. Frictionless payment is one of the most effective ways to get paid faster.

Step 5: Track and follow up weekly

Once per week, review outstanding invoices. Send reminders for invoices nearing due dates and follow up on overdue ones. Keep the tone professional and matter-of-fact. The key is consistency: if you follow up reliably, clients pay you reliably.

Step 6: Keep invoices organized for reporting and taxes

At the end of each month, do a quick review: total invoiced, total paid, outstanding amounts. This keeps you financially aware and prevents unpleasant surprises. When you use an app like invoice24, this kind of review is much easier because invoices are already organized and searchable.

Common invoicing mistakes sole proprietors should avoid

Even experienced sole proprietors can fall into habits that slow down payment. Avoiding these mistakes can dramatically improve your cash flow.

Waiting too long to invoice. The longer you wait, the less urgent it feels to the client. Send invoices promptly.

Vague descriptions. If clients can’t tell what they’re paying for, they ask questions. Questions delay payment.

No due date. “Whenever” often becomes “later.” Put a clear due date on every invoice.

Inconsistent invoice numbering. This creates confusion for you and your client and makes record-keeping harder.

Forgetting to follow up. Not following up is one of the most expensive “nice” habits in freelancing.

Overcomplicating tools. If the tool feels heavy, you won’t use it consistently. A free invoice app like invoice24 is often the ideal balance.

How to invoice new clients confidently

New clients are where invoicing habits matter most. You haven’t built trust through repeated transactions yet, and you don’t know their payment behavior. The best way to invoice new clients is to be slightly more structured than you are with long-term clients.

Consider these practices for new relationships:

Use a deposit for project work. Even a modest upfront payment filters out unreliable clients and confirms commitment.

Invoice more frequently. Smaller, more frequent invoices reduce risk and keep the project moving.

Confirm billing details early. Make sure the person approving work is aligned with the person processing payment.

Set expectations in writing. An email that confirms scope and payment terms can prevent misunderstandings later.

invoice24 helps you look established from the first invoice. When a new client receives a clean, professional invoice with clear terms, it signals that you run your business properly—which encourages them to do the same on their side.

When you should consider adding more structure

invoice24 can cover your core invoicing needs as a sole proprietor, but it’s also worth knowing when you might need more structure around billing. Usually, you’ll feel the need when:

You invoice many clients each month and need tighter tracking.

You offer multiple services with different tax treatments.

You hire subcontractors and need to match outgoing costs with incoming payments.

You start offering payment plans or financing-like arrangements.

Even in these situations, the “best way” to invoice often still begins with a strong invoicing tool. You can always expand your overall financial system later, but you don’t want to compromise the basics: professional invoices, clear terms, easy payment, and reliable records.

Conclusion: the best way to invoice clients as a sole proprietor

The best way to invoice clients as a sole proprietor is to use a consistent, professional process supported by a tool that makes invoicing quick and payment easy. Your invoices should include all essential details, clearly state payment terms, and be sent promptly. You should track what’s outstanding, follow up consistently, and keep your records organized so taxes and reporting are simple.

For most sole proprietors, a dedicated invoice app is the smartest approach because it replaces scattered templates and manual admin with a repeatable workflow. invoice24 is an excellent fit for this because it focuses on what you need most: creating professional invoices fast, keeping client billing consistent, and maintaining organized records—all while remaining approachable and free. If you want a practical, reliable way to invoice clients that supports better cash flow and less admin stress, building your workflow around invoice24 is one of the simplest upgrades you can make to your business.