How to record your time in six-minute units

This page is about England and Wales, and about the person who has to keep the record themselves — the sole practitioner, the self-employed Bar, the small firm with no practice system filling the time in for them. The arithmetic takes a minute to learn. The recording is the part that goes wrong.

Ten to the hour

A unit is six minutes. There are ten in an hour, and because a unit is exactly one tenth of an hour, the number of units and the decimal are the same number. Three units is 0.3 hours. There is no second conversion waiting at the end.

That is the whole reason the profession settled on six minutes rather than five. Five-minute units would be twelve to the hour at 0.0833 of an hour each, and every bill would carry a rounding argument inside it.

Where the six minutes comes from

Not from custom alone. It is written down, in the Practice Direction supplementing Part 47 of the Civil Procedure Rules — the rules for detailed assessment, which is what happens when one party has to pay another’s costs and the court decides how much. Paragraph 5.22(1):

Routine letters out, routine e-mails out and routine telephone calls will in general be allowed on a unit basis of 6 minutes each.

The same paragraph adds that the unit for letters and e-mails out already includes perusing and considering the routine ones that came in, so reading a routine letter in is not a separate charge on top. Checked 20 September 2026.

Two things follow from that, and both get forgotten. It is a rule about what a court will in general allow on an assessment between parties. It is not a rule about how you must record your time, and it is not a rule about what you may charge your own client — that is your retainer’s job. The convention became universal because bills drawn that way are easier to assess, not because anything obliges you to keep your diary that way.

The distinction that gets collapsed

Read the provision again and notice what it is actually about: routine communications. Routine letters out, routine e-mails out, routine telephone calls. One unit each, whether the call took four minutes or seven.

Everything else — attendances, drafting, research, conferences, travel, waiting at court — is charged on the time actually spent. A two-hour conference is charged as two hours because that is how long it took, not because a convention permitted it.

The common error is to take the six-minute unit as a universal rounding rule and put every discrete task up to a full unit. That is not what the provision says, and it produces exactly the bill you would rather not have to justify.

Which way the rounding runs

There are two errors here. They run in opposite directions, and most people only worry about one of them.

Rounding everything up

Take a day with forty discrete pieces of work in it, each genuinely averaging three minutes. That is two hours of work. Put each one up to a full unit and the day bills as four. That is not a rounding artefact, it is a doubling — and it is the kind of pattern that gets a bill questioned as a whole rather than entry by entry.

Not recording the short things at all

The opposite failure, and for a sole practitioner usually the more expensive one. A three-minute call you never write down is not rounded down. It is gone, and so is the note of what was agreed on it.

The position that survives both

Record what actually happened, to the clock, as it happens. Apply the unit convention when the bill is drawn.

That ordering matters more than it sounds. A record kept in real minutes can always be converted into units. A record already rounded into units cannot be converted back. Once the three-minute call has been written down as six minutes, the three minutes is not recoverable — not by you, not by a costs draftsman, and not by anyone asking a fair question about the bill two years later.

What a unit is worth

The guideline hourly rates for 2026 took effect on 1 January 2026, issued by the Master of the Rolls, an uplift of 2.28 per cent on the 2025 figures. They run from £142 an hour for a Grade D fee earner outside London to £579 for a Grade A in London 1. A unit is a tenth of that: between £14.20 and £57.90. Checked 20 September 2026.

They are guideline rates, and that is a real limit worth stating rather than burying. They are the starting point a court uses on assessment between parties. They are not a tariff, and they are not what you charge your own client under your own retainer.

The arithmetic is still worth doing once. At £200 an hour — Grade C outside London on the 2026 figures — a unit is £20. One unit a day, across a working year of 220 days, is £4,400. That is arithmetic rather than a claim about your practice, and your own rate goes through it the same way.

Keeping a record you can bill from

The mechanics, in the order they stop being possible if you leave them.

1. Record against the matter as the work happens, rather than against a mental note to write it up later. A unit is small enough that later is always too late.
2. Write the narrative at the time. “Attendance on client re completion date” takes ten seconds while it is in front of you, and is a small act of archaeology a month afterwards.
3. Mark what is not chargeable as you go — practice admin, CPD, the file you opened by mistake. A record that includes the non-chargeable work is the only one that tells you your real utilisation.
4. Keep the short items short. Write three minutes as three minutes, and let the bill do the rounding when the bill is drawn.
5. Record whether each entry was measured or recalled. If a bill is ever questioned, the difference between a contemporaneous record and a reconstruction is the difference between an answer and an argument.

Where six-minute units fail