Consulting Invoice Template: Hourly, Retainer, Project-Based & Corporate Payment Terms

Consultants bill in different ways: hourly, retainer, or project-based. Each has pros and cons, and corporate clients often have their own payment processes—PO numbers, net 30 or net 60, and expense policies. A solid invoice template adapts to your billing model and meets client requirements. This guide covers hourly vs retainer vs project-based consulting, travel and expenses, payment terms for corporate clients, and example breakdowns for business consulting and IT consulting.

Hourly vs Retainer vs Project-Based

Hourly �?Bill for actual time. Transparent but can feel open-ended to clients. Typical rates: $120�?250/hr for strategy, $150�?300/hr for specialised IT. Best for: ad-hoc work, audits, one-off projects.

Retainer �?Fixed monthly fee for a set scope. Example: $4,000/month for 20 hours of advisory. Unused hours may or may not roll over—define it. Best for: ongoing relationships, predictable income.

Project-based �?Fixed price for defined deliverables. Example: "Strategy document + workshop: $8,500." Best for: scoped engagements where outcomes are clear.

Many consultants use a mix: retainer for steady clients, project-based for discrete work, hourly for overages.

Travel and Expenses

Corporate clients often have strict expense policies. Include:

• Travel �?Flights, trains, mileage (e.g. $0.70/km). Attach receipts or list itemised.
• Accommodation �?When travel requires overnight stay.
• Meals �?Per diem (e.g. $75/day) or actual (with receipts).
• Other �?Materials, software, third-party costs.

Some clients want expenses on a separate report. Others accept them on the main invoice. Ask. And never markup expenses unless agreed—many contracts forbid it.

Payment Terms for Corporate Clients

Corporates move slowly. Expect:

• Net 30 �?Payment due 30 days after invoice. Standard for many.
• Net 45 or 60 �?Larger orgs sometimes push to 45 or 60 days.
• PO required �?Get the PO before you start. Put it on every invoice.
• Payment runs �?They may pay only on specific dates (e.g. 1st and 15th). Invoice in time for the next run.

Include on invoice: "Payment terms: Net 30. PO #12345. Invoice due by [date]." If they're slow, how to chase late payments has scripts for professional follow-up.

Example: Business Consulting Invoice

Client: ABC Pty Ltd | PO: 2026-0342

Item	Hours	Rate	Total
Strategy workshop (facilitation)	6	$180/hr	$1,080
Post-workshop report & recommendations	4	$180/hr	$720
Travel (120 km @ $0.70/km)	1	$84	$84
Subtotal			$1,884
GST (if applicable)			$188.40
Total			$2,072.40

Payment terms: Net 30. Due 20 April 2026.

Example: IT Consulting Invoice (Retainer)

Client: XYZ Corp | Retainer: March 2026

Item	Amount
Retainer �?15 hrs advisory (infrastructure review)	$3,750
Overage �?3 hrs @ $250/hr	$750
Total	$4,500

Scope: 15 hrs included. Used: 18 hrs. Overage pre-approved via email 12 March.

Retainers simplify billing—invoice the same amount each month unless there's overage. For sole traders and freelancers, how to write an invoice as a sole trader covers the essentials. And if you're quoting before the engagement, invoice vs quote explains when to use each. Use EasyInvoice to create invoices from your phone when you're between meetings.

Summary

Choose hourly, retainer, or project-based billing based on the engagement type. Document travel and expenses clearly; follow client expense policies. Corporate clients need PO numbers, net 30 (or longer) terms, and invoices that match their systems. Use real examples—strategy workshop, IT retainer—as templates. A professional consulting invoice gets you paid on time and reinforces your credibility.