Invoice clients early, and you risk looking presumptuous. Invoice late, and you’re funding the job yourself, chasing payment after delivery, staring at debt you may never recover.
So, what’s exactly the right time to invoice clients?
Before work begins. That’s standard professional practice. You win the deal, you invoice the client, and while that’s in motion, you run your AML and KYC checks. Once payment is through and the client is verified, you start the actual work.
Here’s exactly how to do that, what terms to set, and why this protects your firm.
What Does It Mean to Invoice Clients?
An invoice is a legal document that requests payment for services rendered. But beyond requesting payment, it does three things most firms overlook:
- starts the legal clock on your payment terms,
- establishes your professional standing in the client relationship, and
- sets the tone for every billing interaction that follows
When Should Accountants Invoice Clients: Before or After work?
The moment the engagement letter is signed is the right time to invoice. Your client has committed, the scope is agreed, and the price is already on the table. That’s the moment to raise the invoice, run your AML and KYC checks, and wait for both to clear before you open the file. By the time you’re ready to start work, you have a verified, paying client.
That said, the right billing model depends on the type of service you’re delivering. One approach won’t fit every engagement.
How to Invoice Clients: 4 Simple Steps
Invoicing starts before the work does. You set your payment terms, conditions, and timing in the engagement letter. Once it’s signed, you confirm the billing contact, raise the invoice immediately, and set automated reminders until the balance is cleared.
Here is how it looks in practice.
What Are the Right Payment Terms for Accounting Clients?
It depends on the service, but common payment terms include due on receipt for fixed compliance work, direct debit on the first of the month for ongoing retainers, milestone-tied invoicing for project and advisory work, and full upfront payment for any first engagement with a new client.
Here is what the terms actually look like.
Which Day of the Week is Best for Sending Invoices?
Monday before 8 am and Tuesday before the working day starts are the strongest days to send an invoice. Your invoice lands at the top of the inbox at the moment the recipient is clearing their morning backlog with fresh attention. It gets seen, logged, and actioned before the day takes over.
Friday is the worst. The recipient sees it, tells themselves they will deal with it on Monday, and by Monday, it is buried under everything that accumulated over the weekend. That one day of timing adds a week to your average payment time for no reason other than habit.
For recurring retainers, pick a day and stick to it. Clients who receive their invoice on the same day each month begin to anticipate and prepare for it. Predictability conditions prompt payment.
When Should You Follow Up on an Unpaid Invoice & What to Say?
You should follow up on an unpaid invoice as soon as it is due. Yes, you risk coming across as presumptuous, but after 90 days without payment, the probability of collecting drops to 18%. And in most cases, it is not even a refusal to pay. Clients are busy, the invoice slipped down their inbox, and a gentle nudge is all it takes.
Ideally, you would not wait until that day at all.
Most invoicing software offers automated reminders. Set one up for a week before the due date, two days before, and on the day itself. If the invoice remains unpaid after that, send a gentle reminder email or follow up with a call. And for one-off clients, it is a good idea not to deliver the work until payment has cleared.
What Are the Best Practices for Sending Invoices to Clients?
You issue an invoice, start the work, and before the due date the invoice is paid in full without you having to follow up on your own. Then you deliver the work. That is actually possible, and most well-run firms are already doing it.
Here is how you get there.
How to Close the Gap Between Signing & Invoicing
You can close the gap between signing and invoicing by raising the invoice the same day the engagement letter is signed, based on what was already agreed in it. It removes the manual step, keeps everything in motion, and reduces any friction between winning the client and getting paid.
Most firms have a gap because of a handful of common factors:
- manual client setup in accounting software
- no defined invoice trigger in the engagement letter
- unclear billing contacts
- Simply the wrong payment terms for the service type
Any one of these adds days. Most firms are carrying several at once.
Look at these factors across your firm. Better yet, ask clients directly. What made them pay late? What would make payment easier on their end? That ground-level knowledge is more useful than any system change. Fix what clients tell you, not what you assume, and the gap narrows faster than any process overhaul will deliver.
Conclusion
Accountants should invoice clients on signing, before work begins. It keeps cash moving, removes the risk of bad debt, and signals to the client that your firm runs a tight ship.
That said, it is not a one-size-fits-all answer. When you invoice depends on the type of work you are delivering and the client in front of you.
The good rule of thumb is to match the billing model to the engagement. Upfront in full for fixed-fee compliance work: self-assessment, tax returns, and one-off accounts preparation. Deposit plus completion for first-time clients or project work where the scope could shift. Milestone billing for longer advisory engagements, tied to deliverables.
Frequently Asked Questions (FAQs)
An invoice is a formal document requesting payment for services provided. For accountants, it also starts the legal clock on your payment terms and creates a paper trail for both parties. It is the document that sets the tone for how professionally your firm manages its finances.
On signing. Your client has committed, the scope is agreed, and the price is on the table. Invoice at that moment, run your AML and KYC checks, and start work only once both are cleared. You begin every engagement with a verified, paying client.
Upfront for most fixed-fee services. It protects your cash flow, removes the accounts receivable problem, and bills at the point of peak client commitment. Retrospective billing after completion makes collection harder and gives the client no financial stake in the engagement.
Net 30 means the client has 30 days from the invoice date to settle the balance. For most accounting services, it is too long.
Billing is the broader process of managing payments owed. Invoicing is the specific step within it where you formally request payment. In practice, invoicing triggers the billing cycle. Get the invoice out on signing, and the rest of the billing process follows a predictable sequence.
There is no legal deadline, but the longer you wait, the harder collection becomes. After 90 days without payment, the probability of collecting drops to 18%. Best practice is to invoice on signing or within 24 hours of the agreed trigger.
Most accounting software lets you create recurring invoice templates that generate and send automatically on a defined schedule. Set the amount, frequency, billing contact, and payment method once during onboarding. For direct debit collection, connect a payment provider so funds are collected each month without the client needing to act.
