How to Track Billable Hours as a UK Freelancer
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The Records Have Two Audiences
If you bill by the hour, you know the feeling of finishing a project and wondering where half the time went. Undercharging is the obvious cost. The less obvious one arrives when a client questions an invoice and you are reconstructing your week from email timestamps.
There is a second audience for the same records. As a UK sole trader your time logs sit behind the income you declare, and since April 2026 anyone above the Making Tax Digital threshold has been reporting that income quarterly rather than once a year.
This guide covers the three methods that actually work, what each entry needs to contain, and which tools are worth paying for, including the tier detail that catches freelancers out.
Why Time Tracking Slips
It feels like admin for its own sake, right up until it isn’t. A disputed £600 invoice, or an HMRC enquiry with a thin paper trail, changes the calculation quickly.
There is a direct financial cost too. People routinely underestimate how long work takes, and uncaptured time is unbilled time. At £50 an hour, half an hour lost each working day is around £6,500 a year.
Good tracking is not about surveillance. It is about knowing your numbers well enough to price properly and invoice with confidence.
The Three Methods
1. Timer-Based Tracking
Start a timer when you begin, stop it when you finish. A good app makes that one click from a browser or desktop toolbar, and logs the duration against a client and project.
The trade-off: the most accurate method, and the one that depends most on habit. Forget to stop it at lunch, or forget to start it at all, and the record is wrong in both directions. There is also a low-level awareness of the clock that some people dislike.
Best for: freelancers with defined task blocks and several clients running at once.
2. Time Blocking
Plan first. Assign slots to clients and tasks in your calendar, work to the plan, then confirm what actually happened.
The trade-off: lower friction in the moment, but the gap between planned and actual can be wide. If you allowed two hours and it took three, the record only works if you go back and fix it. Otherwise you are billing your optimism.
Best for: people who already plan in a calendar and work in long focused stretches.
3. Retrospective Logging
Reconstruct the day at 5pm from calendar entries, emails, messages and browser history, usually rounding to the nearest quarter hour.
The trade-off: the least friction and the least accuracy. Memory is worst on shallow admin work and interrupted tasks, which is exactly the work that goes unbilled. If you use this method, do it daily. Weekly reconstruction is noticeably worse.
Best for: freelancers working on one substantial project at a time.
What Each Entry Needs to Contain
Whichever method you use, the entry has to survive two kinds of scrutiny.
- Date the work was done, not the invoice date
- Client, clearly named
- Project or matter, such as “Website redesign, phase 2”
- Task description specific enough for the client to verify
- Time spent, in hours and minutes or decimal hours
- Rate, particularly if it varies by client or work type
- Value, so entries reconcile against the invoice
Why Detail Reduces Disputes
“4 hours, project work” invites a question. “2.5 hours: research and outline for quarterly report. 1.5 hours: first draft, sections 1 to 3” gives the client something concrete to agree with. Detail tends to shorten these conversations rather than start them.
The HMRC Side
You must keep records of business income and expenses. HMRC does not prescribe a format for time records, but your logs are what evidences the income on your invoices, and matching logs plus invoices is far stronger in an enquiry than invoices alone.
Keep them for five years after the 31 January filing deadline for the tax year concerned. Records supporting your 2025/26 return therefore need to survive until 31 January 2032.
Making Tax Digital Is Already Running
Making Tax Digital for Income Tax is not a future deadline. It has applied since 6 April 2026 to sole traders and landlords with qualifying income above £50,000, drops to £30,000 in April 2027 and £20,000 in April 2028.
Qualifying income is gross, before expenses, and it adds together self-employment and property income. For a freelancer that means your invoiced total rather than your profit.
Inside the regime you send four quarterly updates, due 7 August, 7 November, 7 February and 7 May, and a Final Declaration by 31 January through compatible software. The updates are cumulative, so each one restates the year to date and an error in one quarter corrects itself in the next.
Time tracking does not feed HMRC directly. Invoices do. But clean time records organised by period make the quarterly cycle a review rather than a reconstruction.
Tools Worth Using
Clockify, and the Tier You Actually Need
Clockify is the usual recommendation for freelancers, and the usual recommendation is wrong about the free tier.
The free plan covers up to five users with unlimited projects and unlimited tracking. What it does not include is billable rates. Exports are PDF only, reporting is capped at a one-month range, and projects are public only. For tracking your own time it is fine. For billing by the hour, the feature you came for is not there.
Prices are in euros, per seat per month, annual then monthly:
| Plan | Annual | Monthly | What it adds for a freelancer |
|---|---|---|---|
| Free | €0 | €0 | Timer, timesheet, mobile and desktop apps, reports limited to a one-month range |
| Basic | €3.99 | €4.99 | Billable rates, historical rates, full exports, time audit |
| Standard | €5.49 | €6.99 | Invoicing, recurring invoices, approvals, QuickBooks integration |
| Pro | €7.99 | €9.99 | Budgets and estimates, alerts, labour cost and profit, expenses |
For an hourly freelancer, Basic at €3.99 is the realistic floor, and Standard at €5.49 is the plan if you want to raise invoices from the same tool. Pro is where margin reporting lives, which matters more if you take on fixed-fee work.
Note the currency. Clockify bills in euros, so a UK freelancer carries a small exchange rate on the subscription.
Todoist for the Task Side
Where Clockify records the time, a task manager records the work. Todoist’s free Beginner plan covers five personal projects, which suits a freelancer with a handful of regular clients, and reminders are included on it, contrary to a lot of older advice. Paid plans are in pounds: Pro at £5 a month billed annually or £7 monthly, and Business at £8 or £10.
The practical value is corroboration. If a client asks what you did on Tuesday, your time entries and your completed tasks tell the same story from two directions.
Accounting Software
If you use FreeAgent, QuickBooks or Xero, all of which have MTD-recognised options, look for an integration that carries time data into invoices rather than retyping it. Clockify’s QuickBooks integration starts on the Standard plan. Xero and FreeAgent connections are worth confirming before you rely on them, as they are not listed on Clockify’s own plan comparison.
Worth knowing if you bank with NatWest, RBS, Ulster Bank or Mettle: FreeAgent comes free with those business accounts, with Mettle requiring at least one transaction a month.
Making the Habit Stick
Anchor it to something you already do. Three minutes reviewing the day’s entries before you close the laptop, attached to the same moment you check final emails.
Use the browser extension. Starting a timer from inside whatever app you are working in removes most of the friction.
Review weekly. Ten minutes on Friday, while the week is still recoverable.
Do not chase perfection. An imperfect log reviewed daily beats a perfect system abandoned in a fortnight.
FAQ
Do I legally have to track hours as a UK freelancer?
Not if you charge fixed fees. If you bill hourly, your time records are what evidence the income you invoice, and HMRC can ask for records supporting your return, so keeping them is strongly advisable rather than optional in practice.
How long should I keep time records?
Five years after the 31 January deadline for the tax year in question. For 2025/26, that means until 31 January 2032.
Can I claim for non-billable time?
Not as an expense. Tracking it is still worth doing, because it tells you your real effective hourly rate, which is the number that should drive your pricing. Software subscriptions used for the business are separately claimable.
What if I work across several clients in a day?
Timer-based tracking, with a separate entry per client, switching as you go. This is the scenario retrospective logging handles worst.
Is Clockify’s free plan enough?
For tracking your own hours, yes. For billing them, no: billable rates start on Basic at €3.99 a seat, and invoicing starts on Standard at €5.49.
How to Track Billable Hours: The Bottom Line
The best method is the one you will keep using. A live timer is the most accurate, time blocking works if you reconcile at the end of the day, and retrospective logging is acceptable only if it happens daily.
The detail matters more than the method: date, client, task, duration and rate on every entry. That combination is what settles a client query, supports your Self Assessment, and keeps your income organised quarter by quarter now that Making Tax Digital applies.
Start simple. A clear naming convention, a five-minute daily review, and a plan that actually includes billable rates.
Prices and plan features correct at time of writing and subject to change, so confirm current details with the provider. Clockify prices in euros; check the converted cost and VAT treatment at checkout. This article is general information about UK tax record-keeping, not advice, and it does not take account of your circumstances. Speak to a qualified accountant about your own obligations.