Sending Invoices: The Complete Guide for Freelancers and Small Businesses

Invoicing is one of those tasks that feels straightforward until the moment it isn't. Do you send the invoice before or after the work is done? How many reminders is too many? And what happens if you forgot to bill a client three months ago — is it too late?

These questions come up constantly, and the answers are more nuanced than most invoicing guides admit. Let's go through them clearly, one by one.

What's the best way to send invoices to clients?

The best way to send an invoice is by email, as a PDF file, with a clear subject line and a short personal message.

That's the standard that works for the vast majority of freelancers and small businesses — because it's simple, traceable, and professional.

Here's what best practice looks like:

❗️ Format: Always send your invoice as a PDF, not an editable file like Word or Excel. A PDF cannot be accidentally modified, looks consistent across devices, and is widely accepted by accounting teams.

Subject line: Be specific.
“Invoice #INV-2025-042 — Branding Project — Due May 15” is far better than “Invoice attached.” A clear subject line improves searchability and reduces the chance of your email being ignored.

Message body: Keep it short. One or two lines explaining what the invoice covers, the total due, and the due date is enough.

✅ Hi [Client Name],

Please find attached invoice #INV-2025-042 for the branding project, totaling €2,400. The payment is due by May 15.

Let me know if you have any questions.

Best regards,
[Your Name]

Delivery method: Email is the default. However, some companies (especially larger ones) require invoices to be submitted via internal supplier portals. Always confirm this early in the project.

Invoicing software: If you bill regularly, using invoicing software reduces friction. Tools like InVault allow you to create, send, and track invoices — including whether the client has opened them — which simplifies follow-ups.

❓ One practical detail: always send the invoice to the right person. The person you work with is not always the one responsible for payments. Ask early: “Who should I send invoices to?”

Do you send an invoice before or after payment?

The timing depends on the type of work and agreement. There is no single rule, but there are clear patterns.

After delivery (most common):
For project-based work, invoices are typically sent after the work is completed and delivered.

Before work begins (deposit):
For larger projects, it is standard to request an upfront payment. Industry data (including surveys by accounting platforms like QuickBooks in recent years) consistently shows that a significant share of small business invoices are paid late — often cited around 40–50%, depending on the study and methodology. A deposit helps reduce that risk.

Typical range: 30–50% upfront.

Recurring work (retainers):
Invoices are usually sent at the beginning of each billing period.

Milestones:
For long projects, invoicing at milestones is common.

Example:
€6,000 project → 30% upfront (€1,800), 30% at approval (€1,800), 40% at delivery (€2,400).

Key principle:
Avoid waiting until the end of a long project to send your first invoice.

How soon after completing work should you send an invoice?

As soon as possible — ideally the same day.

This is not just about cash flow. When the work is fresh in the client’s mind, invoices are more likely to be processed quickly.

Some industry reports suggest that invoices with clearly defined payment terms (e.g., Net 30) are paid significantly faster than those without them. For example, figures often cited in invoicing studies show averages such as ~30–35 days vs. ~50+ days, though exact numbers vary by source and sample.

Takeaway: clear terms and fast sending both matter.

A practical rule: treat invoicing as the final step of project delivery.

How often should you send invoice reminders?

A structured, polite reminder schedule works best.

For a standard Net 30 invoice:

• 5–7 days before due date: Friendly reminder (optional)
• On due date: Short, neutral message
• 3–7 days late: Polite follow-up
• 10–14 days late: Firmer reminder
• 30 days late: Formal notice
• 60–90 days late: Consider escalation

Many sources and payment behavior studies suggest that a large share of late payments happen due to oversight rather than refusal — often informally estimated at over 50%, though exact figures vary. This is why reminders are effective.

Tip: Tuesday–Thursday mornings tend to have higher response rates.

How late is too late to send an invoice?

From a practical standpoint: send it within 30 days.
From a legal standpoint: it's usually not too late.

Practically:
The longer you wait, the more friction you create. Clients may forget details or question delays.

Legally:
Invoices do not “expire,” but legal enforcement does.

Typical limitation periods:

• United States: Usually 3–6 years (varies by state and contract type)
• United Kingdom: 6 years
• Germany: 3 years from the end of the calendar year
• France: 5 years (commercial claims)

Example:
If you forgot to invoice for work done three months ago — send it now. This is common and usually not a problem.

VAT and invoicing deadlines (EU note)

If you are VAT-registered, invoicing timelines may be regulated.

In many EU countries, tax invoices must be issued relatively quickly — often within a few weeks (sometimes around 15 days) after the supply date for B2B transactions. However, exact rules vary significantly by country, so always check local regulations.

How to store invoices properly

Sending invoices is only half the job — storing them correctly is just as important.

Poor invoice management can lead to:

• lost payments
• accounting issues
• tax compliance problems

Best practices for storing invoices:

• Keep digital copies (PDF is standard)
• Use consistent naming (e.g., INV-2025-042_ClientName)
• Store in one system (cloud storage or invoicing software)
• Back up regularly
• Keep records for required periods (often 6–10 years depending on country)

For a detailed breakdown of storage systems, naming conventions, and legal requirements, see our full guide on invoice storage.