- Billable hours are working time attributed to revenue-generating client work under the terms of the engagement. On hourly work, those hours may directly determine what the client is charged; on fixed-fee, retainer and other models, they can instead be used to understand delivery cost, utilisation and margin.
- Non-billable hours are working time the business needs but cannot invoice, such as internal meetings, admin, training and business development.
The split between the two drives utilisation, pricing, staffing and profitability in every professional-services firm.
Here’s the thing about that split, though.
Most guides treat it as an invoicing question, as if every firm still billed purely by the hour. In practice, consultancies, agencies and accounting practices now mix hourly work with fixed fees, retainers and outcome-linked engagements, and the billable versus non-billable distinction means something slightly different in each one.
This guide covers the definitions and examples first, then the utilisation maths, and then what “billable” actually means across the billing models your firm probably already runs.
Here are the key takeaways before we get into the detail.
- Billable hours are client work you can invoice; non-billable hours keep the business running but never reach an invoice
- Utilisation rate is billable hours divided by available working hours, and professional-services firms averaged 66.4% in 2025 against a commonly cited 75% optimal threshold (SPI Research)
- The same task can be billable on one engagement and non-billable on another; the client agreement decides
- On fixed-fee, retainer and outcome-linked work, tracked time stops being an invoice input and becomes your cost and margin instrument
- Firms that decide billability at setup, through timesheet categories and rates, tend to leak less time than firms that decide it entry by entry
For a growing services firm, this distinction doesn’t live in a spreadsheet on its own. It sits inside connected operations, where projects, schedules, time, expenses and invoicing share one system. That’s the territory of Professional Services Automation, and it’s worth knowing the label because the most complete tools for managing billable time increasingly work this way rather than treating timesheets in isolation.
What Are Billable Hours?
Billable hours are the working hours your team spends on tasks that a client has agreed to pay for, directly or under a contract. They typically include project delivery, client meetings, research performed for a specific engagement, revisions the client requests, and communication about the client’s work. Billable hours are the raw material of revenue in any firm that sells expertise by the engagement.
What counts as billable is ultimately a contractual question, not a philosophical one. Drafting a deliverable for a client is billable almost everywhere. Travelling to a client’s office is billable in some agreements and absorbed in others. The engagement terms decide, which is why firms that write billability into their contracts and project setup argue about it far less at month-end.
Industries built on billable time include business and management consultancies, law firms, accounting and finance practices, creative and digital agencies, engineering firms and IT services companies. Different industries, same underlying economics.
What Are Non-Billable Hours?
Non-billable hours are working hours spent on activities the business needs but cannot invoice to any client. They include internal meetings, administrative work, proposal writing and pitching, training and professional development, internal process improvement, and marketing or networking. Non-billable time is not wasted time. It is the operating cost of running and growing the firm, and it deserves the same tracking discipline as billable work.
The useful way to think about non-billable hours is as investment with an expected return. Training raises the quality of future billable work. Business development creates the next engagements. Process improvement reduces the admin drag on everyone. The problem is never that non-billable hours exist. The problem is not knowing where they go, because untracked non-billable time is where capacity quietly disappears.
Examples of Billable and Non-Billable Work
Billable work is client-facing and invoiceable under the engagement; non-billable work keeps the firm running but never reaches an invoice. In practice, you’ll find the classification is easiest to teach with concrete examples. These lists reflect common professional-services norms, and your engagement terms always take precedence.
Let’s start with the tasks that are usually billable.
No. | Billable Tasks |
|---|---|
1 | Working directly on client project deliverables |
2 | Client meetings, calls and emails about the engagement |
3 | Research and analysis performed for a specific client |
4 | Revisions and changes the client requests |
5 | Project supervision and quality control on client work |
6 | Preparing client-facing reports and presentations |
7 | Travel for client engagements, where the contract allows it |
8 | Onboarding and training the client’s team as part of delivery |
And these are the tasks that usually stay non-billable.
No. | Non-Billable Tasks |
|---|---|
1 | Internal planning and strategy meetings |
2 | Administrative work and scheduling |
3 | Staff training and professional development |
4 | Writing proposals and pitching new business |
5 | Marketing, networking and industry events |
6 | Internal projects and process improvement |
7 | Timesheet, invoicing and general office admin |
8 | Breaks and internal social time |
And then there’s the grey zone, which is where most disputes actually start. The table below shows the classifications that genuinely depend on the engagement.
Task | Billable or Non-Billable |
|---|---|
Meetings about a client held internally | depends on the engagement terms |
Drafting contracts and statements of work | depends on whether it’s pre-sale or in-delivery |
Travelling to client premises | depends on the contract |
Waiting time during client engagements | depends on the agreement |
Preparing invoices for a client | usually non-billable, occasionally agreed otherwise |
The pattern across that third table is worth stating plainly. The same activity can be billable on one engagement and non-billable on another, and the client agreement decides. Firms that settle these classifications in the contract and in project setup, rather than leaving them to individual judgement at entry time, get more consistent data and fewer awkward billing conversations.
Billable vs Non-Billable Hours: The Main Difference
The main difference is whether the time is attributed to revenue-generating client work or to the internal operation of the firm. On hourly engagements, billable hours may appear directly on the client invoice. On fixed-fee, retainer and outcome-based work, the hours may not be invoiced individually but still matter for measuring delivery cost and margin. Non-billable hours are generally absorbed by the firm as part of its operating cost.
Both are real work, both consume capacity, and both need tracking, but only one appears on an invoice.
Aspect | Billable Hours | Non-Billable Hours |
|---|---|---|
Definition | time spent on client work that can be invoiced under the engagement | time spent on work the business needs but cannot invoice |
Who pays | the client, through invoicing | the firm, as overhead |
Revenue effect | supports revenue-generating client work; may directly drive invoicing on hourly engagements | supports revenue indirectly |
Typical examples | delivery, client meetings, engagement-specific research | admin, training, internal meetings, business development |
Why you track it | accurate invoicing and revenue capture | cost visibility, capacity planning, process improvement |
Metric it feeds | utilisation and realization rates | overhead ratios and capacity analysis |
What Is a Billable Expense?
A billable expense is a cost your firm incurs specifically for a client’s project that the client has agreed to reimburse. Common examples include travel booked for an engagement, project materials, software licences bought for a client build, and subcontractor fees. Billable expenses sit alongside billable hours on the invoice and follow the same logic; the engagement terms decide what qualifies.
Two quick rules keep billable expenses clean. First, the expense should be directly attributable to the specific engagement, reasonable and necessary. General office costs and anything personal stay out. Second, documentation is what protects you, both with the client and at tax time. Receipts attached to expense records, marked billable at entry, flow onto invoices without a month-end archaeology project.
Billable expense income, if you’ve seen the term in your accounting software, is simply the revenue side of the same coin. When a reimbursed expense is invoiced to the client, it’s recorded as income that offsets the original cost.
Utilisation: The Metric That Connects the Two
Utilisation rate is the percentage of available working time spent on billable work. The formula is straightforward.
Utilisation rate = billable hours ÷ available working hours × 100
So if a consultant records 30 billable hours in a 40-hour working week, their utilisation is 30 ÷ 40 = 75%. Run the same calculation across the whole delivery team and you get firm-wide utilisation, which is one of the fastest single reads on the commercial health of a services business.
Now, what should that number be? According to SPI Research’s Professional Services Maturity Benchmark, average billable utilisation across professional services was 66.4% in 2025, below the 75% level SPI identifies as an optimal benchmark.
That does not mean every employee or every professional-services firm should target the same percentage. Utilisation expectations should vary by role, seniority and operating model. Delivery-heavy roles can reasonably carry higher billable expectations than managers and senior leaders whose responsibilities also include mentoring, business development, hiring and internal management.
The more useful approach is to set role-specific utilisation targets, compare them with actual performance, and investigate sustained gaps rather than treating one industry-wide percentage as a universal rule.
Legal services show how wide the gap can be, and it’s a useful reality check for every discipline. Clio’s Legal Trends Report puts the average lawyer’s utilisation at 38% in 2025, which works out to about 3.0 billable hours captured in an eight-hour day. You can be at your desk all day and still bill a fraction of it, which is exactly why the number needs measuring rather than guessing.
⚠️ One caution before you set targets.
Utilisation is a balance, not a maximisation exercise. Very high billable targets leave less room for training, business development, internal management and unexpected delivery work, so the right target needs to be sustainable for the role rather than simply as high as possible.
Utilisation vs Realization Rate
Utilisation and realization measure two different leaks.
- Utilisation asks how much of your available time became billable work.
- Realization asks how much of that billable work was actually invoiced, calculated as billed hours divided by billable hours recorded.
Time gets written off between the two through discounts, write-downs and forgotten entries, and it can sit unbilled as work in progress far longer than anyone intends. A related leak is budget overrun, where a project consumes more hours than estimated, so the effective hourly rate falls even though every hour was recorded.
Clio’s 2025 data shows lawyers invoicing about 2.6 of the 3.0 billable hours they capture, an 88% realization rate. A firm can have healthy utilisation and still bleed revenue at the realization step, which is why finance leads watch both.
What a Utilisation Report Shows
A utilisation report shows recorded time split into billable and non-billable, as a percentage of available hours, over a chosen period.
In Avaza’s reporting, you can group and filter that view by person, project, category or user tag, which is what turns a single percentage into something you can act on. Utilisation flat but one project consuming double its planned hours? Now you know where to look. One person at 95% while a teammate sits at 40%? That’s a scheduling conversation, not a performance one.
One UK software and IT services firm of 100-plus people reads a weekly Staff Utilisation report in Avaza alongside its project and expense data, which lets leadership spot over- and under-utilisation and rebalance assignments. At that scale, complete and approved time data is what keeps the reporting reliable enough to drive staffing decisions.
Utilisation reporting turns a vague sense of “we’re busy” into something managers can investigate by person, project, category or user tag.
Book a call to see how Avaza can support utilisation, time tracking and billing across your firm’s delivery teams, or create a free account to explore the platform yourself.
Billable Hours Across Engagement Models
What counts as billable changes with the engagement model, but the need to track effort doesn’t. Consultancies and agencies increasingly mix time and materials work with fixed fees, monthly retainers and outcome-linked engagements, and the meaning of “billable” shifts as the model changes. To be honest, this is where most billable-hours guides stop short, because they explain the split as if hourly billing were the whole story. For a modern services firm it isn’t.
Engagement Model | How the Client Is Charged | What “Billable” Means Here | What Time Tracking Is For |
|---|---|---|---|
Hourly / time and materials | agreed rate per hour worked | every qualifying hour appears on the invoice | invoicing accuracy and revenue capture |
Fixed fee | one agreed price for a defined scope | no hour is invoiced individually; the fee covers the scope | measuring delivery cost against the fee to protect margin |
Retainer | recurring fee for ongoing access or an hours allowance | hours or retainer credit are drawn down rather than generating line items | tracking retainer burn and spotting over-servicing |
Outcome-linked | payment tied to results delivered | billing is detached from hours entirely | knowing what the outcome cost to deliver |
Read the right-hand column again, because that’s the argument of this whole section.
On hourly work, a timesheet is an invoice input.
On every other model, it’s a cost and margin instrument. A fixed-fee project that was scoped at 120 hours and quietly consumed 190 didn’t fail at invoicing; it failed at cost visibility, and without tracked time nobody finds out until the margin has already gone. A retainer client absorbing half the team’s month looks profitable on the invoice and isn’t. An outcome-linked engagement can be priced brilliantly and delivered at a loss, and only the effort record can tell you which happened.
Moving away from hourly billing does not remove the need to understand delivery effort. On fixed-fee, retainer and outcome-based engagements, tracked time becomes an internal input for understanding project cost, margin and future pricing. Combined with cost rates and historical delivery data, it helps firms scope future work using actual effort rather than assumptions.
How to Track Billable and Non-Billable Hours Well
Good tracking is mostly decided before anyone fills in a timesheet. The firms that get clean data share a few habits, and none of them involve heroic diligence at entry time.
1️⃣ First, decide billability at setup, not per entry. In practice this means timesheet categories with billable and non-billable settings baked in, so the classification is made once by whoever configures the project rather than four hundred times a month by everyone else.
In Avaza’s timesheets, categories carry the billable flag along with optional billable and cost rates, and each project can bill by a project-wide hourly rate, per-person rates or per-category rates, so the structure matches how the engagement was actually sold. Categories can also be marked payable or non-payable, which keeps what you invoice the client separate from what you owe contractors and staff for the same hours.
Setting these conventions once, at account setup, is what makes every later timesheet consistent.
2️⃣ Second, make entry easy enough that it happens daily. Timers on any device, entries created straight from tasks, and daily or weekly views cover the different ways people actually work. Time entered several days later is more likely to rely on memory and lose detail, so encouraging same-day entry generally produces more reliable records.
3️⃣ Third, put a review step between recording and invoicing. Timesheet and expense approval workflows, where enabled, let organisations require human review before approved records move further into their billing and reimbursement processes. From there, unbilled time and expenses flow onto invoices without re-keying, and retainer or recurring billing runs on schedule with the tracked detail behind it.
4️⃣ Fourth, close the loop with reporting. Utilisation by person, project, category or user tag, unbilled time surfaced before month-end, and exports when finance wants the raw data. Customers describe the result as having their data at their fingertips, with less admin time and fewer errors from copying numbers between systems, and that’s really the point of connecting the chain from time through to invoice in one platform.
Why Non-Billable Hours Deserve the Same Discipline
Tracking non-billable hours is what turns overhead from a mystery into a managed cost. It’s tempting to track billable time carefully and let everything else fall into an untracked bucket, but that bucket is where the answers hide.
Tracking non-billable hours tells you which clients consume disproportionate unbillable support, which is a pricing signal for the next renewal. It shows you how much partner and senior time goes into proposals, which is the real cost of your sales motion. It reveals admin work that could be automated or delegated, and internal projects that have quietly become full-time jobs.
It also surfaces conversion opportunities.
Firms reviewing non-billable time regularly tend to find work that should have been billable all along, such as client change requests absorbed as goodwill or scope creep nobody priced. You can only convert what you can see.
How Do You Reduce Non-Billable Hours?
You reduce non-billable hours by automating admin, tightening scope and meeting discipline, and converting hidden billable work, not by tracking less. The aim is to shrink the low-value slice of non-billable time while protecting the investment slice, because training and business development are where future revenue comes from.
Strategy | What It Looks Like in Practice |
|---|---|
Automate the admin layer | timers, timesheet reminders, invoices generated from tracked time instead of re-keyed |
Tighten internal meetings | shorter defaults, clear agendas and fewer unnecessary attendees to reduce avoidable internal meeting time |
Define scope precisely | clear statements of work reduce unbillable rework and “quick favours” |
Convert hidden billable work | review non-billable logs monthly for client work absorbed as goodwill |
Delegate deliberately | senior people carry the highest-value hours; push admin to systems, not upward |
How Many of Your Working Hours Should Be Billable?
There is no single billable-hours target that works across every professional-services role. SPI Research reported average billable utilisation of 66.4% in 2025 and identifies 75% as an optimal benchmark at the industry level, but individual targets should still vary by role and responsibility.
Delivery-focused consultants can carry higher billable expectations than senior leaders whose non-billable responsibilities include sales, hiring, mentoring and firm management. The important discipline is to define those expectations deliberately and review actual utilisation against them consistently.
Targets also only work if the workload behind them is realistic, which is where capacity forecasting across team workloads comes in. And remember that the answer changes with your engagement mix, because on fixed-fee and retainer work the target that matters is delivery cost against the fee, not billable percentage alone.
Should You Share Billable-Hours Detail with Clients?
Yes, in almost every hourly or retainer relationship, transparency about billable hours builds trust and pre-empts invoice disputes. Clients dispute surprises, not numbers.
A clear breakdown of where time went, at whatever level of detail the engagement warrants, demonstrates that the fee reflects real work and makes renewal conversations easier. On fixed-fee and outcome-linked work you generally won’t share hours, since the client bought a result rather than time, but you’ll still want the internal record for your own margin analysis. The practical middle ground is to keep detailed records always, and share them at the grain the billing model calls for.
Frequently Asked Questions
What Is the Difference Between Billable Hours and Actual Hours?
Actual hours are the total hours a person works in a period, billable or not. Billable hours are the subset of actual hours that can be invoiced to clients under an engagement. The gap between the two is your non-billable time. Utilisation is measured differently, it’s billable hours against available working hours, not against actual hours worked.
Can the Same Task Be Billable on One Project and Non-Billable on Another?
Yes. Billability is set by the engagement terms, not by the task type. Travel, internal meetings about a client, and contract drafting are all billable under some agreements and absorbed under others. That’s why firms define billability in the contract and configure it at project setup, so the classification is consistent rather than left to individual judgement.
How Should Larger Services Firms Manage Billable and Non-Billable Time Across Multiple Teams?
Larger services firms need consistent project categories, billability rules and approval workflows across teams rather than letting each project manager classify time differently. Standardising those rules at project setup makes utilisation reporting comparable across offices, practices and delivery teams.
The same principle applies to approvals. When time feeds invoicing, project reporting and utilisation analysis, clear approval ownership helps ensure leadership is working from complete and reliable actuals.
What Is a Good Utilisation Rate?
SPI Research reported average billable utilisation of 66.4% across professional services in 2025 and identifies 75% as an optimal benchmark. Individual targets should still vary by role and responsibility.
A delivery consultant can reasonably carry a higher billable expectation than a practice leader who also handles sales, mentoring, hiring and internal management. Firms should therefore set targets by role and review them alongside project margins, workload and non-billable responsibilities rather than applying one percentage across the organisation.
What Are the Downsides of the Billable-Hours Model?
The model can pressure people to log more hours than is healthy, penalise efficiency because faster work bills less, and tempt inflated entries when targets are aggressive. Those pressures are part of why firms diversify into fixed-fee, retainer and outcome-linked pricing. The discipline that survives every model is effort tracking, since cost and margin visibility matter regardless of how the client is charged.
What Is the Fastest Way to Improve Billable-Hour Capture?
Enter time daily. Reconstructed timesheets lose real billable work, and delayed entry is the most common capture leak. Beyond that, decide billability at setup through categories, run timers instead of estimates, and review unbilled time before month-end so recorded work actually reaches an invoice.
Track Both Sides of the Ledger in One Place
The firms that win on this topic aren’t the ones with the highest utilisation targets. They’re the ones that can actually see the split, week by week, across every engagement model they run. Avaza connects timesheets, projects, expenses, invoicing and reporting in one platform, so teams can define how time is categorised, review timesheets and expenses through approval workflows where enabled, and analyse utilisation by person, project, category or user tag.
Book a call to discuss how Avaza would handle your firm’s mix of hourly, fixed-fee, retainer and non-billable work across multiple delivery teams. If you prefer to explore it independently, you can also create a free account and test the workflow with your own data.
Full plan details are available on Avaza’s pricing page.
