Time Tracking for Consultants: Bill Every Client Accurately
SPI Research put billable utilization across professional services firms at 66.4% in 2025, the lowest figure in the history of its benchmark survey and a long way short of the 75% most firms aim at. If you're a solo consultant reading that, it lands differently than it does for a firm. A firm with a number like that has a resourcing problem. You probably have a record-keeping one, because the hours you worked and the hours you can put on an invoice are rarely the same list.
Consulting work bills badly for a specific reason: it arrives in fragments. A call here, a contract review there, forty minutes on a proposal that quietly becomes ninety. By Thursday, Tuesday afternoon is a smudge, and the entry you type is a guess rounded down, because guessing downwards feels safer than being challenged on it.
Where consulting hours actually go missing
Not in the big blocks. Nobody forgets the all-day workshop. What disappears is the twelve-minute call you took walking to the car, the email thread that took three replies and twenty minutes of thinking, the "quick look" at a deck someone sent on Sunday night. Each one feels too small to be worth writing down, and that's how they accumulate.
Say six of those slip past you in a normal week, ten minutes each. That's an hour. At £150 an hour across a 46-week working year, you've handed back roughly £6,900. You didn't discount it or lose an argument about it. It just never made it onto a timesheet.
There's a second leak, and it's subtler. When you reconstruct a day from memory you round downwards, every time. Nobody sits on Friday afternoon and generously decides Tuesday's call was longer than it felt. So the gap between worked and billed isn't random noise, it's a consistent one-way discount you apply to yourself. The fix is boring: shorten the distance between doing the work and recording it.
Record in minutes, bill in tenths
The professional services standard is the tenth of an hour, six minutes to a unit. Ten units make an hour, so 0.1 is a six-minute email, 0.3 is an eighteen-minute call, 1.4 is an hour and twenty-four minutes. Law firms, accounting practices and most consulting shops bill this way, and corporate procurement departments already know how to read it, which saves you a conversation.
Quarter-hour billing still exists, and it's worth being careful with. Rounding a five-minute phone call up to 0.25 is defensible once. Do it eleven times on one invoice and a finance reviewer starts marking your line items, which is how a write-down begins. Tenths give you a smaller unit to be honest in.
Whatever you choose, put the rounding rule in the engagement letter. "Time is recorded in increments of one tenth of an hour" is a sentence that costs nothing to include and settles the question before it becomes a dispute over one line on invoice number four. And record the real minutes as you go. Converting to tenths is arithmetic you can do at invoice time; inventing the minutes afterwards is not.
Write the entry your client's finance team will read
The person approving your invoice usually wasn't in the room. They're matching a dollar figure against a purchase order and a memory of what you were hired for. "Meeting, 2.0" gives them nothing to approve, so they query it or trim it.
Compare that with "Reviewed Q3 vendor contracts, drafted risk summary for the steering committee, 1.4". Same work, same rate, completely different conversation. Name what you touched and what came out of it. You're not writing an essay; you're giving somebody a reason to say yes without picking up the phone.
Block billing is the habit worth breaking: a whole day collapsed into a single 7.5-hour entry with a vague label reads as an estimate even when it isn't. Writing entries in a shorthand only you can decode is the other one. If you're going to spend the time typing it, type the version the client can read, because you're going to paste it onto the invoice anyway when you bill for hourly work.
One system across every engagement
Most consultants end up with a per-client patchwork: a spreadsheet for the big retainer, the client's own portal for the enterprise account, and a mental note for everyone else. It works until the week you're busy, which is the week it matters. We've written separately about tracking time across multiple clients, and the short version is that the number of systems should be one.
Structure it as a project per engagement rather than a project per client. A client with a discovery phase and an implementation phase at different rates is two projects, and keeping them apart means the profitability question ("which of these was actually worth doing?") has an answer at the end. Attach the rate to the project itself rather than typing it onto each line, so there's one place to get it wrong instead of forty.
Mark billable and non-billable as you go, too. Proposal writing, your own bookkeeping and the hour you lost to a broken VPN are all real work that nobody pays for directly, and they belong on the record even though they never reach an invoice. That split is what makes your utilization figure mean anything, and it's what tells you whether your rate is carrying the unpaid half of the week. If the distinction is fuzzy, our guide to billable versus non-billable hours draws the line with examples.
Retainers, caps and the scope conversation
Consultants on a monthly retainer often stop tracking hours, on the reasonable grounds that the invoice is the same number either way. Then eight months later the engagement feels wrong and there's no evidence for why.
Track it anyway, and divide. A £4,000 retainer that quietly consumes 40 hours a month is an effective rate of £100 an hour. If you priced it expecting 20 hours, you're working at half your rate and calling it a good client. That's an arithmetic problem you can fix in a renewal conversation, but only if you can say "here are the last six months" instead of "it feels like a lot lately".
The same goes for capped fixed-fee work. When you hit the cap in week three, the log is the difference between a change order and an awkward silence. A dated list of what was asked for and when tends to settle that conversation faster than an impression that the job got bigger.
Your time log is a US tax record too
Something changed for 2026 that makes your own records more load-bearing than they used to be. Under the One Big Beautiful Bill Act, the reporting threshold for Form 1099-NEC rose from $600 to $2,000 for tax year 2026, with annual inflation adjustments from 2027. Plenty of clients who used to send you a 1099-NEC in January now won't have to.
The income is still taxable and still goes on Schedule C. All that's disappeared is the paperwork that used to arrive to remind you of it. If a client pays you $1,800 across three small projects in 2026 and files nothing, your invoices and your time log are the record. Keep them.
The rest of the US self-employed calendar hasn't moved. Self-employment tax runs at 15.3% (12.4% Social Security plus 2.9% Medicare), figured on Schedule SE with half of it deductible against income. If you expect to owe $1,000 or more, estimated payments for 2026 fall due on April 15, June 15 and September 15, 2026, then January 15, 2027. The IRS generally expects you to keep supporting records for three years, and longer in some situations, so a time log that survives past the invoice is doing double duty. If you're newer to all of this, our guide to time tracking for independent contractors covers the ground-level version, and invoicing as a US freelancer covers W-9s and payment terms. None of this is tax advice, and a CPA who knows your state is worth the fee.
What the free tools still cover in 2026
The tooling picture got worse for consultants this year, specifically in the part that matters to someone who bills by the hour.
Clockify capped its free plan at five users and moved billable rates, bulk edit and CSV or Excel export onto paid plans in 2026. PDF export survives, and free reports are limited to a month of range at a time, so pulling a quarter for a client review is a paid action now. We went through the whole list in what changed in Clockify's free plan.
Toggl Track keeps a decent free tier for up to five users, but billable rates have always sat on Starter, around £9 per user per month billed annually. Approvals and profitability reporting are Premium, roughly £18. The timer is excellent. The billing math costs money.
Harvest is built around invoicing, which suits consultants, but its free plan allows one seat and two active projects. A consultant with three clients has already outgrown it.
This is the gap VibaCloud fills. It connects to your Outlook or Google calendar and turns the meetings already sitting there into a draft weekly timesheet, so most of your week is recorded before you type anything. You tag each entry to a client and project, mark it billable or not, and the project's rate totals the value as you go. Any week exports to Excel or PDF for the invoice. That's the free tier, with no card and no seat count. If you'd rather compare options first, we keep an honest roundup of free timesheet apps that still track billable hours.
The calendar-first part is worth dwelling on for consulting specifically, because your calendar is already the most accurate record of your week that exists. The client call has a start time, an end time and a title that names the client. Starting from the calendar you already keep means Friday is a review job rather than an archaeology job.
The bottom line
Most consultants start tracking properly the week after an argument. A client queries an invoice, or a retainer turns out to have swallowed twice the hours it was priced for, and the resolution is to be more careful from here on. The problem is that the record you need in that moment covers the six months before it, and you can't go back and write it. That's the whole case for keeping the log in the quiet weeks too, when nothing is in dispute and it feels like paperwork for its own sake.
Frequently asked questions
What billing increment should consultants use?
Tenths of an hour, six minutes to a unit, is the professional services standard and the one corporate finance teams expect to see. Quarter-hour rounding inflates short tasks and invites write-downs. State the increment in your engagement letter.
What is a good utilization rate for a consultant?
Firms generally target 75%, and SPI Research recorded an average of 66.4% across professional services in 2025. Solo consultants usually run lower, because business development, proposals and admin all come out of the same week.
Do consultants still get a 1099 in 2026?
Often, but less than before. The 1099-NEC reporting threshold rose from $600 to $2,000 for tax year 2026, so smaller clients may not file one. The income is still reportable on Schedule C, which makes your own invoices and time records the primary evidence.
Should I track time on a fixed-fee or retainer engagement?
Yes. The hours do not change the invoice, but they tell you the effective hourly rate you are working at, and they are what you bring to a renewal or a scope conversation when the work has grown past what you priced.
What is the best free time tracking tool for consultants?
It depends on what you need free. Clockify moved billable rates and CSV export to paid plans in 2026, Toggl puts billable rates on Starter, and Harvest's free plan allows two projects. VibaCloud keeps billable rates and export free and builds the timesheet from your calendar.
