Selling time narrows your promise to something you can keep: you will turn up, apply your attention to whatever is in front of you, and stop when the agreed hours end. Nobody has to guess how deep the trouble goes before quoting, which is why discovery, debugging, rescue jobs and anything touching an unfamiliar system belongs here. A buyer who wants a fixed figure for an unexamined codebase is asking you to price their uncertainty, then carry it. Time-based work also removes the defensive padding that infects estimates: there is no need to price the worst case into a number when the worst case simply bills as it happens. What you give up is leverage. A day is capped by the calendar, so income rises only by charging more per day or working more of them, and speed is rewarded with an earlier finish rather than a larger fee. That is a genuine flaw and the usual prescription is value-based pricing, which assumes the buyer can verify an outcome they could not specify. Many cannot and will not pay for one. The realistic middle is to stay on time, price the day properly, and make sure the day is defined tightly enough that its edges are not donated.
Set the figure from the year rather than from a salary you envy. Start with everything an employer used to absorb on your behalf and now does not: pension, equipment, software, insurance, accountancy, sick days, holiday, training and the empty weeks between engagements. Then work out how many days you can sell once selling, invoicing, admin and learning have taken their share, because that number is far smaller than the working days in a calendar and it is the divisor that tells the truth. Raise the rate on new enquiries first, where there is no relationship to renegotiate, and give existing clients notice of the change with a date attached rather than an apology. Discount for certainty, never for volume: a block booked months ahead is worth something, while a promise of more work later is worth what such promises usually are.
- What a day is. The hours it contains, and whether a morning counts as a whole one. Half-days are where this model becomes hourly billing with extra steps.
- What starts the clock. Travel at the client's request, meetings, reading their documentation, sitting blocked on an access request nobody chased. Decide before it happens, because deciding afterwards always costs you the argument.
- The smallest bookable unit. Single scattered days fragment a week and cost more in lost context than they bring in. Name a minimum and let the diary breathe.
- Notice on reserved dates. Dates held for one client are dates refused to another. State the point at which a cancelled booking is invoiced regardless, and state it before you are holding anything.
- A ceiling with a stopping point. Open-ended frightens finance departments. Put an estimate in days, plus an undertaking to pause and re-agree before passing it, into the statement of work. It costs nothing and answers the main objection to buying time.
- A date to revisit the figure. A rate agreed at the start of a long engagement becomes a silent discount by its second year. Put the review month in the agreement while nobody minds.