A Tuesday 10 AM assignment and a Tuesday 8 PM assignment are not the same product. The evening job pulls an interpreter away from dinner, draws from a smaller pool of willing professionals, and is harder to fill on short notice. Every agency knows this intuitively; the difference between a profitable agency and a stressed one is whether that intuition is written down as pricing policy — and whether the software applies it automatically.
Here's how the premiums typically work, and the decisions you need to make for your own rate card.
After-hours: adder or multiplier?
The first structural choice for out-of-business-hours (OBH) work is between a flat adder — say, a fixed dollar amount per hour on top of the base rate — and a multiplier, like time-and-a-quarter or time-and-a-half on the whole job.
- Flat adders are transparent and easy to explain on an invoice: base rate plus an evening premium, two visible line components. They also keep the premium proportional in absolute terms — the client with a higher negotiated base rate isn't paying a larger evening premium than anyone else.
- Multipliers scale with the base rate, which some agencies prefer precisely because premium clients then carry proportionally more of the after-hours cost. They're familiar from overtime norms, but they can produce eyebrow-raising totals on already-high base rates.
Neither is wrong. What matters is consistency, and defining when the window starts: a common pattern is treating weekday evenings after a set hour, plus weekends and holidays, as OBH. Write the boundary down to the minute — a 5:00 PM start time and a 5:01 PM start time should never be a judgment call.
Rush: pricing the countdown
Rush is about notice, not clock time. A booking placed a month ahead can be filled calmly through normal channels; the same booking placed six hours out requires immediate broadcast, rapid responses, and often a premium to motivate an interpreter to rearrange their day. Agencies typically define one or more rush windows — bookings inside a set number of hours before the start time — each carrying its own adder or multiplier, with the shortest-notice tier priced highest.
The critical operational detail: rush should be computed from when the booking was placed relative to the start time, automatically. The moment rush becomes something a dispatcher remembers to add, two things happen — it gets forgotten on busy days (you eat the cost) and applied inconsistently across clients (you get the awkward call).
When both apply: the stacking question
Sooner or later a client books an 8 PM job at 2 PM the same day. Now both premiums are in play, and you need a stacking policy before it happens, not during the invoice dispute after.
Three common answers, each defensible:
- Full stacking — both premiums apply, on the logic that the job is genuinely both harder to staff and at an inconvenient hour. Simplest to automate and to explain.
- Greater-of — only the larger premium applies. Softer on the client, and common where after-hours work is frequent enough that stacked totals would strain relationships.
- Capped stacking — both apply up to a maximum combined premium. A compromise that mostly appears in negotiated enterprise contracts.
Whichever you pick, it should live in the rate schedule — applied by the system, printed clearly on the invoice, identical for every client on that schedule. And remember the premium usually has two sides: many agencies pass a share of rush and OBH premiums through to interpreter pay, because the interpreter is the one actually rearranging their evening. Your platform should let the billing side and the pay side of a premium be set independently.
Decide your stacking policy before the 2 PM booking for the 8 PM job — not during the invoice dispute after.
Rule of thumb
The supporting cast: minimums and cancellations
Two adjacent policies keep the premium structure coherent. Billing minimums — commonly two hours for on-site work — ensure a short evening assignment still compensates the interpreter's travel and disruption; the minimum applies first, then premiums compute on the billed duration. Cancellation windows mirror your rush logic: if a booking cancelled inside 24 hours bills at some or all of its value, that's the same recognition that short notice has a cost, pointed in the other direction. Clients understand the symmetry when both policies are written down together.
Make the software carry the policy
None of this is complicated arithmetic. What makes it hard in practice is that it's conditional arithmetic performed dozens of times a week under time pressure — exactly the work humans do inconsistently and software does perfectly. A proper rate engine lets you define the OBH window, the rush tiers, the stacking rule, and the minimums once per rate schedule, then prices every job from its own date, time, and booking timestamp with the premium visible as its own line on the invoice.
The payoff isn't just accuracy. It's that when a client questions an evening invoice, the answer is a policy — agreed, written, uniformly applied — rather than a dispatcher's recollection. Premiums priced by policy get paid. Premiums priced by memory get negotiated, one uncomfortable phone call at a time.