Billing in six-minute increments without quietly overcharging

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 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.

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.

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.