Round the merged daily total for a task, not each entry. Four two-minute calls about the same matter on the same day are 8 minutes of work. Rounded separately at 6-minute increments they bill 0.4 hours; rounded as one 8-minute block they bill 0.2. Both are defensible as policy, only one matches what most clients believe they agreed, and the difference compounds across a year.
The increment is not the question. Where it applies is.
Six-minute billing is settled practice in legal work and common in consulting. The American Bar Association's model rule on fees requires that a fee be reasonable and that the basis for it be communicated to the client, which is the standard the rest of this argument is measured against. A tenth of an hour is the unit; anything shorter rounds up to it. Nobody argues about that.
The argument, when it happens, is about something the engagement letter almost never specifies: what gets rounded. Each individual entry, or the day’s total for that piece of work? Two tools can both honestly claim "6-minute increments" and produce invoices that differ by a fifth.
The increment is in the contract. Where it is applied is in the software, and almost nobody checks which one they bought.
The arithmetic, on a normal Tuesday
Take a real shape of day. One matter, one client, four interruptions: a two-minute call, a three-minute reply, another two-minute call, a one-minute confirmation. Eight minutes of work, honestly recorded as four entries because that is how the day happened.
| Method | What is billed | At $400/hr |
|---|---|---|
| Rounded per entry | 4 × 0.1 = 0.4 hours | $160 |
| Rounded on the merged daily total | 8 min → 0.2 hours | $80 |
| Exact minutes, no increment | 0.133 hours | $53.33 |
Per-entry rounding bills exactly double the merged method here, and three times the actual time. Nothing dishonest happened. The timer was accurate, the entries were real, the increment was the one agreed. The arithmetic simply ran at the wrong level.
Now scale it. A practice with two or three fragmented days a week, at that rate, is a five-figure annual difference produced entirely by a setting nobody discussed.
Why it always errs upward
Rounding up per entry can only ever increase the total, never decrease it, and it increases most for the clients who interrupt you most. That is an unfortunate correlation: the client who calls four times a day is billed disproportionately more than the one who sends a single email, for the same eight minutes of your attention.
What a client believes they agreed to
Ask a client what "billed in six-minute increments" means and almost all of them describe the merged version: work gets rounded up to the nearest tenth of an hour. Very few imagine that answering three short questions about the same matter creates three separate minimums.
This matters beyond fairness. An invoice that a client reads and disagrees with does not get refused; it gets delayed. It sits in accounts payable while somebody works out whether to ask. The query costs you a fortnight of cashflow and an uncomfortable email, and you will usually write off the disputed portion anyway to keep the relationship comfortable. The aggressive rounding did not earn the money; it just made the invoice slower.
There is a straightforward test. If you would be uncomfortable explaining your rounding method in a sentence to the client, it is not the method you should be running.
Getting it right, and writing it down
Three things, in order of how much they matter:
- Round the merged daily total per task, not each entry. Then several short entries about one matter on one day behave exactly as the client expects, and detailed record-keeping stops silently inflating the bill.
- Keep the entries separate on the invoice anyway. Merging for the arithmetic is not the same as hiding the detail. A client who can see 09:14 discovery call, 11:02 follow-up question has far less to query.
- Put the method in the engagement letter. One sentence: "Time is billed in six-minute increments, applied to the daily total for each matter." It costs nothing to write and removes the entire argument in advance.
Which increment to pick, and what each one costs a client
Six minutes is the convention in legal work, but it is not the only choice and it is not automatically the fairest. The increment decides the size of the minimum charge, and the minimum charge is what a client actually feels. The table below is the same 8 minutes of genuine work under each common setting, billed with the merged daily total at $200 an hour.
| Increment | Billed hours | Amount | Overcharge on 8 real minutes |
|---|---|---|---|
| To the minute | 0.13 | $26.67 | none |
| 6 minutes | 0.20 | $40.00 | $13.33 |
| 15 minutes | 0.25 | $50.00 | $23.33 |
| 30 minutes | 0.50 | $100.00 | $73.33 |
| 60 minutes | 1.00 | $200.00 | $173.33 |
The jump from 6 to 15 minutes looks small on one entry and is not small across a year. Where it becomes indefensible is 30 and 60 minutes, which turn a two-minute phone call into a half hour or an hour. Those settings exist because they were convenient before software, and they survive because nobody revisits them.
There is a second effect that the table does not show. A large increment punishes exactly the work you want clients to bring you. If a two-minute question costs the client half an hour, they stop asking two-minute questions, and the small advisory contact that keeps you in the room quietly stops happening. The increment is not only a billing setting, it is a price on being available.
The one sentence to put in the engagement letter
Whatever you choose, write it down before the first invoice rather than after the first argument. The American Bar Association's model rule on fees requires that a fee be reasonable and that the basis for it be communicated to the client, preferably in writing and before or within a reasonable time after starting work. Consultants are not bound by it, but it is a good standard to borrow.
Time is billed in six-minute increments, rounded up, applied to the total time spent on each matter each day rather than to each individual entry.
That sentence takes ten seconds to add and removes the entire argument in advance. It also tells a prospective client something useful about you, which is that you thought about it at all.
None of this is about billing less. You can watch the merged-total method run on real entries in the free demo, which bills the same way the product does. Track everything, including the twenty minutes of reading before a call that most people never record at all. Recovering that is worth far more than anything per-entry rounding adds, and unlike rounding, nobody disputes it.