There's a moment most agencies never notice because nothing on the client side changes. You cross 50,000 outbound segments in a calendar month, and your per-segment cost quietly drops from $0.02 to $0.016 — a 20% cut on the send rate — while your client keeps paying you exactly what they paid last month. That gap is either margin you pocket, a discount you share, or a wedge you use to close the next deal. Most agencies don't have a policy for it because they've never done the math on what it's actually worth.
Full disclosure: I work for Ready, so this walkthrough uses our tiers. But the decision framework applies to any provider with automatic volume pricing — the question of "who keeps the discount" is universal, and getting it wrong leaves real money on the table.
The mechanic: the discount applies to you, silently
Here's the part worth being precise about. On Ready, the Growth rate is applied automatically once your account passes 50,000 segments in a calendar month. You don't pick a plan. You don't call anyone. You don't sign anything. The segments past the threshold bill at $0.016 instead of $0.02.
Two things follow from that:
- It's account-level, not client-level. If you run 40 sub-accounts under one Ready account, their volume aggregates toward your threshold. One busy month across the whole book can tip you into Growth even when no single client is high-volume.
- Your clients see nothing. Their rebill rate is whatever you set in your contract. The carrier pass-through — a flat $0.0045/segment, billed separately and never marked up — doesn't change either. So the entire 20% is yours to allocate.
That last point is the whole article. The provider handed you a discount. Now you decide what happens to it.
Blended-rate reality: your cost isn't $0.016
Before you spend the savings, price it correctly, because the discount only applies to segments above 50,000 — not to your whole volume. This is the mistake that inflates every back-of-napkin margin calc.
Say you send 80,000 segments in a month:
- First 50,000 × $0.02 = $1,000.00
- Next 30,000 × $0.016 = $480.00
- Send-rate subtotal = $1,480.00
- Blended send rate = $1,480 / 80,000 = $0.0185/segment
Not $0.016. Your blended rate at 80k is $0.0185, and it keeps falling toward $0.016 the more you send past the line. We worked this exact scenario in more detail in the 80,000-segment blended-rate breakdown — if you're modeling a specific volume, start there.
Add the carrier pass-through ($0.0045 × 80,000 = $360) and your all-in cost for the month is $1,840, or $0.023/segment blended. That's the number your rebill has to beat.
Option 1: Pocket it
The simplest move. You rebill at your existing rate, your cost drops, and the delta drops into margin.
Worked example — you rebill at $0.03/segment (a common ceiling before clients start auditing the line item; more on that in the markup-ceiling piece) and send 80,000 segments:
| Line | Amount |
|---|---|
| Client pays (80,000 × $0.03) | $2,400.00 |
| Your send cost (blended) | $1,480.00 |
| Carrier pass-through | $360.00 |
| Gross margin | $560.00 |
Now compare the same month if you'd never crossed the threshold and everything billed at $0.02:
- Send cost would be 80,000 × $0.02 = $1,600
- Margin = $2,400 − $1,600 − $360 = $440
The automatic tier added $120 of margin on this account this month, with zero effort and zero client conversation. Multiply across a book of accounts and it's a meaningful line. This is the honest default: you took on the volume risk, the discount is your reward.
Option 2: Share it to reduce churn
The counter-argument: a client who feels squeezed audits the line item, and an audit is where markups die. Passing part of the discount along can be cheaper than replacing a churned account.
Say you drop the client's rate from $0.03 to $0.028 at renewal, framed as a volume reward. On 80,000 segments:
- Client pays 80,000 × $0.028 = $2,240
- Your cost (send + carrier) = $1,840
- Margin = $400
You gave back $160 of margin versus pocketing it. Whether that's smart depends entirely on the account's churn risk and lifetime value. A $2,240/mo client you'd struggle to replace? Cheap insurance. A price-insensitive client who never checks? You just donated $160. Know which one you have before you volunteer a discount.
Option 3: Use it to win the price-sensitive deal
The most strategic use. The Growth tier isn't just a discount on current volume — it's a lower marginal cost on new volume. That means the next high-volume client you close costs you less to serve than your existing ones did at the same size.
If your account is already past 50,000 segments, a new client's sends land in Growth territory from segment one. You can quote them aggressively — say $0.025/segment when your competitors are quoting $0.03 — and still keep healthy margin:
- Client pays 20,000 × $0.025 = $500
- Your marginal send cost (already in Growth) = 20,000 × $0.016 = $320
- Carrier = 20,000 × $0.0045 = $90
- Margin = $90 (18% on a rate that undercuts the room)
The client that pushes you deeper into Growth also earns the better rate for everyone. That's a virtuous loop worth planning around deliberately — the crossover-planning post covers how to time onboarding so you tip the threshold and hold it.
The billing-model decision underneath all this
None of the above matters if your client-billing model doesn't pass volume through cleanly. Two shapes:
- Per-message rebill — you bill for what you send. The tier discount flows straight to your margin, and heavy months are covered because the client pays for the volume that created the cost. This is where the Growth tier shines.
- Flat monthly SMS fee — you charge a fixed number regardless of send volume. Here the discount is pure upside until a client has a monster month and blows past your assumptions, at which point your flat fee has to absorb the overage. The tier discount cushions that, but doesn't eliminate the risk.
If you're weighing the two, the per-message vs flat-rebill comparison walks through which model survives a heavy send month. Short version: per-message rebill and automatic volume pricing are a natural pair, because the discount and the volume that triggered it live in the same account.
Don't let the carrier fee quietly reverse the win
One trap. If you rebill at a rounded "$0.03 all-in" and forget the carrier pass-through is a separate real cost, you're not keeping $0.01 — you're keeping $0.0055, because $0.0045 of every rebilled dollar is a pass-through you owe. The Growth discount improves the send side of that equation, but it does nothing for the carrier line. Model both separately or the tier win gets silently eaten. We laid out exactly how this happens in the hidden carrier-fee margin post — worth reading before you set a rebill rate.
The practical takeaway
The 20% Growth-tier drop past 50,000 segments is automatic, account-level, and invisible to your clients. That means the money is yours to direct — but only if you know it exists and price it against your blended rate, not the headline $0.016.
Three plays, in order of who benefits:
- Pocket it — the honest default; you carried the volume risk.
- Share a slice — cheap churn insurance for high-LTV, price-aware accounts.
- Reprice new deals — your lowest marginal cost is where you win the competitive quote.
Run your actual send volume through the blended-rate math above before you touch a rebill number. If you're not on Ready yet and want to model it against your real book, you can start with 2,500 free credits, no card and see where your monthly volume lands relative to the threshold — or read how agencies actually make margin reselling SMS for the full rebilling picture. The discount's already there in the pricing. The only question is whether it shows up in your margin or slips past you unnoticed.