Best Invoice Software for Consultants 2026 (Reviewed & Ranked)
FreshBooks is the best overall pick for consultants, combining time tracking against billable hours, retainer support, and proposal-to-invoice conversion in one place. For consultants billing large corporate clients through procurement systems, pairing it with a clear PO-number workflow matters as much as the software itself.
Affiliate Disclosure: This article contains affiliate links to FreshBooks. We may earn a commission if you sign up through our links, at no extra cost to you.
Consultants bill differently depending on the engagement — hourly against a retainer, fixed project fees, or a mix of both across several concurrent clients. The right invoicing tool needs to track time accurately, handle retainers cleanly, and produce invoices formal enough for corporate procurement processes.
What Consultants Need From Invoicing Software
- Accurate time tracking — billed against specific clients and projects, ideally with a timer, not just manual entry
- Retainer support — tracking hours or budget drawn down against a pre-paid retainer, not just one-off invoices
- Multiple concurrent clients — a clean way to separate and report on each client’s billing without confusion
- Corporate-ready formatting — PO number fields, formal line-item detail, and export formats procurement departments expect
Best Invoice Software for Consultants, Compared
| Tool | Best For | Time Tracking | Retainers |
|---|---|---|---|
| FreshBooks | Independent consultants, small consulting firms | ✅ Built-in timer | ✅ Yes |
| QuickBooks Online | Consultants who also need full accounting | ✅ Via add-on | Manual setup |
| Billtoolbox Invoice Generator | Occasional one-off consulting invoices, free | ❌ Manual entry only | ❌ No |
1. FreshBooks — Best Overall for Consultants
FreshBooks
Track billable hours against specific projects with a built-in timer, convert tracked time directly into an invoice, and manage retainers cleanly — all with a client portal that keeps billing communication in one place.
For the full breakdown of pricing tiers, see our complete FreshBooks review.
2. QuickBooks Online — Best If You Need Full Accounting Too
Consultants running a larger practice with multiple contractors or employees often outgrow invoicing-first tools and need the fuller accounting picture QuickBooks provides — payroll, more detailed financial reporting, and a larger integration ecosystem.
3. Billtoolbox Invoice Generator — Best Free Option for One-Off Engagements
If consulting is a side engagement rather than your main income, a free tool without a monthly subscription may be all you need. Our free invoice generator lets you build a clean, itemized invoice with your logo and export it as a PDF in minutes — no sign-up required.
Billing Corporate Clients as a Consultant
Many consulting engagements run through a corporate client’s procurement or accounts payable department rather than a single point of contact, which means invoices typically need a PO number, may need to be submitted through a vendor portal, and often run on longer payment cycles than direct-to-individual billing. See our full guide on how to invoice a company as a freelancer, and get the engagement scoped clearly upfront with our guide on how to write a business proposal that wins clients.
Frequently Asked Questions
Should consultants bill hourly or by retainer?
Retainers give more predictable income and reduce the admin overhead of tracking every hour, but they require confidence in estimating ongoing scope. Many consultants use hourly billing for new or project-based clients and move to retainers once the relationship is established and recurring.
What should a consulting invoice include that a standard invoice doesn’t?
A PO number if the client requires one, a clear breakdown of hours or milestones covered by the invoice, and the specific engagement or project name if you’re running multiple concurrent engagements with the same client.
How do I track time across multiple consulting clients accurately?
A dedicated time-tracking tool tied to specific client/project tags — built into platforms like FreshBooks — is far more reliable than reconstructing hours from memory or a general calendar at invoicing time.
Final Thoughts
Consulting billing gets complicated fast once retainers, multiple clients, and corporate procurement requirements enter the picture — a tool built around time tracking and retainer management, like FreshBooks, earns its cost back quickly compared to reconstructing hours and formatting invoices manually.
Try FreshBooks — Built for Consultants
Time tracking, retainers, and corporate-ready invoices in one place.
Disclaimer: This article is for informational purposes only and does not constitute financial or legal advice. Pricing and features are subject to change — verify current details directly with each provider before signing up. Affiliate links are present in this article.