Invoicing a client starts with creating a workflow process to reduce the time from tracked hours to invoice. You'll need a time-tracking tool and a professional invoice sent within 24 to 48 hours with a "pay now" link, or a PDF sent via email with your payment terms and details.
How you handle invoicing as a consultant affects more than your admin load. It also determines how fast you get paid.
Here's an example: You do the work, start creating the invoice, and then a client call usurps your attention. The invoice gets pushed to tomorrow and then to Friday. Before you know it, it's the end of the month, and you have a pile of unsent invoices.
Seems harmless on the surface, until you consider it takes 28 days on average to get paid. The longer you delay invoicing, the more cash flow pressure builds, and that's before accounting for the billable time you'll lose chasing payments.
There's a second cost too. An invoice protects your business from client disputes. It documents what work was done, when it was delivered, and your payment terms, and it records your taxable income.
Get the timing, the format, and the payment methods right, and getting paid stops being a month-end headache.
When should you invoice a consulting client?
Knowing when to send invoices helps set clear expectations with clients. Depending on the type of agreement you've made, you could invoice at the following points:
| Billing model | When to invoice | Best for |
|---|---|---|
| Upfront deposit | Before work begins (25-50% of total) | New clients or larger projects, as a filter against unreliable payers |
| Milestone billing | As each milestone is signed off | Defined projects with clear phases (research, draft, final delivery) |
| Project completion | Once, on delivery | Shorter, well-scoped work with an established client |
| Retainer | At the start of each recurring schedule outlined in your agreement | Ongoing monthly projects, access and availability |
| Fixed cadence (weekly or biweekly) | On the same day every cycle, regardless of milestones | Ongoing hourly or time-and-materials work |
Across all five, you want to aim to invoice as close to the triggering event as possible, usually within 24 to 48 hours.
Read more: Hourly Billing Guardrails: Clauses and Change Orders to Prevent Scope Creep
Send the invoice the day you finish the work
Kiaro turns tracked time into a professional invoice with a pay-now link, so month-end never becomes a pile of unsent invoices. Free forever, no credit card.
How long should you give a client to pay once invoiced?
As a consultant, you can use different payment timelines to dictate when a client should pay before late fees will apply.
Most invoicing software defaults to Net 30, meaning the client has 30 days to pay from the invoice date. However, that's not always beneficial for cash flow management or for how your client's accounting process works.
Here are the most common terms for consultants and when it makes the most sense to use each one.
| Term | Best for | Benefit | Drawback |
|---|---|---|---|
| Due on receipt | Small invoices, one-off work, or a new client with no payment history yet | Fastest possible cash; nothing to chase | Can feel abrupt with new or larger clients who expect standard terms |
| Net 7 | Small businesses without a formal AP process; the default for most solo consultants | Protects cash flow while still reading as standard practice | Larger clients' accounts payable systems sometimes can't process anything shorter than Net 30, regardless of what's on the invoice |
| Net 15 | A middle ground, common with clients who have a fixed fortnightly payment run | A workable middle ground for clients on a fortnightly payment run | Doesn't strongly favour either side: not fast enough to meaningfully help cash flow, and not standard enough to be the automatic default |
| Net 30 | Any client with a formal accounts payable process, where shorter terms wouldn't get you paid any faster | Universally accepted; rarely questioned by a client's finance team | The longest wait of the "standard" terms; defaulting to it out of habit costs you weeks of cash flow you didn't need to give up |
| Net 60+ | High-value retainers or multi-year contracts, where the monthly amount justifies the wait | Sometimes the price of entry for larger retainers or enterprise clients | Ties up a significant amount of cash for two months or more, with real risk exposure if that client's situation changes |
How to create a professional consulting invoice
Offering a professional service means there is no excuse to use Word docs or Excel spreadsheets for your invoicing.
It looks unprofessional, doesn't convey a premium service, and increases the time you'll spend working out the maths for your billable hours.
To avoid any hassles with invoicing, it's best practice to use a free or paid invoicing tool. With both options, you'll get customisable professional templates and access to features that'll streamline your invoicing, like time tracking, billing increments, and invoices with built-in payments.
| Free invoicing tools | Paid invoicing software | |
|---|---|---|
| Best for | Consultants looking to keep costs lean and send only a handful of invoices a month | Consultants who need access to automation and complex time-to-invoice billing features for a clean workflow |
| Cost | $0 | Typically $9-$40+/month |
| Templates | Professional, customisable | Professional, customisable |
| Getting paid | Usually manual: client pays via bank details on the invoice | Built-in pay-now links |
| Automation | Little to none: you create and send each invoice yourself | Auto-numbering, recurring/retainer billing, overdue reminders |
Read more: The best invoicing software for consultants in 2026
What must every consultant invoice include?
Here's what every consulting invoice template must include.
- Your details: Your business name, address, email, and your tax or VAT number.
- Client details: Include their legal trading name, point of contact for payments, address, and tax number.
- Invoice details: Always include a unique invoice number (invoicing software will automatically generate one for you), the invoice date, and the payment due date.
- Line items: Your line item should explain the work you completed, including details of deliverables, hours logged, and your hourly rate. Show the calculation and the subtotal for each item.
- Taxes, VAT, and compliance notes: Include any applicable taxes or VAT charges to stay compliant.
- Expenses and reimbursements: Depending on your contract and scope of work, you may need to bill clients for expenses such as software, stock photos, or travel.
- Discounts, deposits, or partial payments: Apply each applicable option to your invoice, and use the notes section to detail any previous payments and the outstanding balance.
- Payment terms and methods: Detail how you accept payments and whether any late-fee policies apply.
Remember to keep a copy of every invoice you send, along with proof of payment. Retention rules vary by country, so check what your local tax authority requires to stay compliant.
Want a free invoicing template designed for how consultants bill? Download Kiaro's invoice template with the two settings that matter most: net 7 instead of net 30, and sending it the day you finish rather than at the end of the month.
What should you do if a client doesn't pay on time?
At some point in your consulting business, a client isn't going to pay on time.
Maybe the invoice email got buried, the client forgot, or there was a payroll glitch. In most cases, a polite reminder a few days after the due date solves the problem.
However, there are the odd few cases where you'll need to pull out the late fee clause in your contract and apply it. In more serious cases, you may need to threaten legal action.
Not every unpaid invoice is a timing problem. Sometimes a client disputes the invoice itself, questioning the hours logged, the rate, or whether a deliverable was completed. In these cases, you can use your time-tracking logs, emails, and other supporting documentation to resolve the issue before chasing payment again.
The good news is that you can avoid most payment disputes with the following strategies:
- Don't start work until your client has signed a legally binding contract that explicitly states your payment terms and conditions
- Take an upfront deposit
- Use a time-tracking tool
- Invoice immediately and accurately
- Adding a "Pay Now" button for online payments can help you receive payments 4x faster
- Use invoicing software to automate follow-ups and apply late fees automatically
Read more: Invoice-to-Cash Churn Warning System: Signals to Track and Fix First
Create accurate invoices on autopilot
Creating a clear invoicing workflow that integrates with your time tracking and includes a "pay now" button helps you get paid faster, reduces admin, and builds a professional reputation.
As you set up your processes, use our free Getting Paid Kit. It has everything you need, from invoice templates to deposit-ask templates, a scope clause for contracts, and a late-payment email sequence.
Frequently asked questions
How soon after finishing work should consultants send an invoice?
Within 24 to 48 hours. The longer you wait, the more likely it is that details get fuzzy, and the later the payment clock effectively starts, since most payment terms count from the invoice date, not the date you did the work.
Do consultants need a business bank account to invoice clients?
Not legally. If you're a sole trader, you can invoice from and get paid into a personal account. It's still worth opening a separate one, since mixing personal and business transactions makes bookkeeping and tax season far harder than they need to be.
Do consultants need to charge VAT?
Only if you're VAT-registered, and that depends on your location and turnover. Outside VAT jurisdictions, such as most of the US, the equivalent is state sales tax, and whether it applies to consulting services varies by state.
Can consultants invoice clients internationally?
Yes. Tools like PayPal, Wise and Payoneer let you accept international payments, or you can send clients your bank transfer details, including the SWIFT code. Your invoice should also include the agreed-upon billing currency to avoid exchange rate disputes.