How to track billable hours: a five-step method that ends in an invoice

What counts as billable time

Billable hours are the hours you can charge a client for under your agreement with them. Non-billable hours are everything else you work: sales calls, admin, internal meetings, learning, and fixed-fee work that isn’t charged by the hour.

The line between the two is set by each client’s contract, not by how the work feels. Travel, short calls and quick email replies are the usual grey areas. Some agreements bill them and some don’t. Write the rule down for each client before you start tracking, and record those tasks either way. A non-billable entry still tells you how long the client’s work really takes.

A few examples for a small consulting or design firm:

• Usually billable: project work, client meetings, research for a specific client, revisions the client asked for.
• Usually non-billable: proposals, invoicing itself, team meetings, tool setup, training.
• Depends on the agreement: travel time, short calls, email, out-of-scope requests on a fixed-fee project.

Track non-billable time too. It shows how many hours a fixed fee really covers, and it gives you a utilization number (billable hours divided by hours worked) when you price the next project.

Step 1: Decide where time lives

Pick one place where every hour is recorded. Time split across a calendar, a notes app and memory is where hours go missing.

You have three realistic options. A spreadsheet works for one person with a few clients. A timer app works for capture, but someone still has to copy the hours into invoices. A tracker connected to your invoicing tool removes the copying step.

Whichever you choose, each entry needs the same six fields:

1. Date
2. Duration, or start and end time
3. Client
4. Project or engagement
5. Billable or not
6. A short note on what was done

If a field is missing, the entry can’t be invoiced cleanly. Make the client and project required, even in a spreadsheet.

Step 2: Capture time as it happens

The most reliable way to track billable hours is to record them when the work happens, not at the end of the week. Reconstructing a week from memory drops the short tasks first: a ten-minute call, a quick fix, an email that took half an hour. Each one is small, but over a month they add up to real money.

Habits that make same-day capture stick:

• Start the timer before the task. If you forget, add the entry as soon as you notice, with your best estimate.
• Use shortcuts for repeat work. A saved timer for “Client A, monthly reporting” takes one click instead of four fields.
• Catch timers left running. A timer left on overnight creates an entry nobody believes. Use a tracker that warns you, or check your running timer before you close your laptop.
• Do a two-minute daily check. At the end of the workday, scan your entries for gaps longer than an hour and fill them while you still remember.
• Log the small stuff. If your agreement bills calls and emails, track them. If it doesn’t, track them as non-billable so you can see what they cost you.

For a team, the same rules apply to everyone. Ask people to track daily, and check that nobody’s week has empty days before you start invoicing.

Step 3: Record enough detail to defend the invoice

Every invoice line should answer the client’s question: “What did this cover?” The note on each entry is where that answer comes from.

A useful note is short and specific. Compare these:

• Weak: “Work on project.”
• Useful: “Revised onboarding emails 2–4 after Tuesday’s feedback.”
• Weak: “Call.”
• Useful: “Call with Dana re: Q3 budget and the reporting change.”

You don’t need a paragraph per entry. One line that names the deliverable or the decision is enough. Good notes also save you time later. When a client questions a line months after the invoice, the answer is already written down.

Step 4: Apply rates and rounding the same way everywhere

Two rules change the number on the invoice more than anything else: which rate applies, and how time is rounded. Decide both once and apply them to every entry.

Rates. Most firms need more than one rate. Different clients pay different rates, strategy work costs more than implementation, and a senior consultant bills at a different level than a junior one. Write down which rate wins when two apply. A common rule is that the most specific rate wins: a rate for this person on this project beats a project rate, which beats a person’s default rate.

Rounding. Billing increments are usually 6 minutes (a tenth of an hour), 15 minutes or 30 minutes. Choose one, then choose the direction. “Nearest” rounds 1 h 47 min to 1 h 48 min in 6-minute increments. “Up” rounds 1 h 41 min to 1 h 42 min. Put the rule in your engagement letter so the client sees it before the first invoice. Apply it the same way on reports and invoices, so the totals always match.

Calculating the amount. Billable amount = rounded hours × rate. For example, 1 h 47 min at $120 an hour, rounded to the nearest 6 minutes, is 1.8 hours. 1.8 × $120 = $216. Without rounding, it’s 1.78 hours, or $214. That small gap is why the rule has to be written down and applied consistently.

Step 5: Review, invoice and lock

Before you invoice, review the period for each client:

1. Filter your entries by client and date range.
2. Fix any entry that’s missing a project or a note.
3. Check that billable and non-billable flags are right.
4. Compare the hours with any budget or estimate you gave the client, and talk to them before the invoice if the work ran over.

Then build the invoice from the entries, not from memory or a summary. Group lines by project or task, or list each entry, whichever the client expects.

After the invoice goes out, lock the entries it covered. If an entry changes later, the record no longer matches what the client paid, and the same time can end up on the next invoice too. In a spreadsheet, move billed rows to a separate tab or mark them with the invoice number. A good tracker does this for you.

Worked example: billable hours in Wave

Wave is a popular accounting and invoicing tool for small businesses, but it doesn’t track billable time. Wave Payroll has timesheets, but they’re for paying employees, not for invoicing clients. So hours have to come from somewhere else. Our guide to Wave time tracking options compares the four ways to do that.

The manual method works for a handful of clients. Create a service in Wave for each rate you charge, such as “Consulting, hourly” at $120. At the end of the period, total each client’s rounded hours from your tracker or spreadsheet. Add the service to an invoice with the hours as the quantity, and attach the timesheet if the client wants the detail.

A connected tracker skips the copying. With Swell, you review each outgoing line with the hours, rate and notes behind it, then create a draft invoice in Wave and send it from Wave. Entries on the draft are locked, so they can’t be edited or billed twice. How tracked hours become a Wave invoice walks through it step by step. Swell starts at $15 a month with a 14-day trial, and connecting it needs Wave Pro or Wave Advisors.

Spreadsheet or time tracker?

Option	Setup	Monthly effort	Main risk	Cost
Spreadsheet	A template with the six fields	Track, total, retype each invoice	Missed or duplicated lines	Free
Timer app + manual invoice	Install and set up clients	Retype totals into invoices	Rates and rounding applied by hand	Free plans are common
Tracker connected to invoicing	Connect your accounting tool once	Review and send	Needs the right accounting plan	Subscription

A spreadsheet is enough when one person bills a few clients at one rate. Once several people track time, rates differ by project or person, or you send more than about five hourly invoices a month, the retyping becomes the slow and risky part. That’s the point to move to a tracker that builds the invoice from your entries.

If you work with consultants or freelancers, see how this looks in practice for consultants and freelancers.