Per-Lot Rebate Math: What You Can Pay Back and Still Profit

Every rebate IB eventually asks the same question in a different form: how much of the spread or commission can you pay back to a trader before the deal stops making sense for you? Rebate rates look generous when a broker quotes them as a headline number — "$7 per lot" or "up to 90% of the spread" — but the number that actually matters is what is left over per lot after you pay the trader, cover your own costs, and absorb the volume swings that come with running a lot-rebate business. This article works through that math directly, with worked examples, so you can set a payout rate you can defend at any volume level instead of guessing and finding out you were underwater three months in.

What "per-lot" actually means before you do any math

A standard lot is 100,000 units of the base currency; a mini lot is 10,000; a micro lot is 1,000. Rebates are almost always quoted per standard lot equivalent, so the first step in any rebate deal is converting whatever mix of lot sizes your traders actually place into standard-lot terms — a trader running 0.10-lot micro trades all day generates a fraction of the rebate volume of one running 5-lot positions, even with the same number of tickets.

Two numbers drive the whole calculation:

1. Broker payout per lot — what the broker pays you, either as a flat pip rebate (e.g. $8 per round-turn standard lot) or as a spread-mark-up share, where you receive a cut of the spread the broker adds on top of raw interbank pricing.
2. Trader payout per lot — what you pass back to the client, which is your product, and which determines whether the client sees your offer as worth switching for.

The gap between those two numbers, multiplied by monthly lot volume, is your gross margin before any fixed costs.

Building the per-lot margin formula

The core formula is simple, but each input hides real variability:

Per-lot margin = Broker rebate per lot − Trader rebate per lot − Allocated cost per lot

• Broker rebate per lot usually rises with a volume-tier structure — a tiered-commission-structure where your blended rate improves as your book's monthly volume crosses thresholds (for example, a lower per-lot rate under 100 lots/month, a mid rate from 100-500, and a top rate above 500). Know which tier your realistic near-term volume lands in — don't price your trader payout off a top tier you haven't reached yet.
• Trader rebate per lot is what you advertise. It has to be competitive against other cashback sites covering the same broker, but every dollar you add here comes straight off your margin.
• Allocated cost per lot covers everything that isn't the rebate itself: payment processing fees on payouts, customer support time, marketing spend to acquire the client, and any commission-account infrastructure or rebate-calculator tooling you run to track and reconcile trades. Divide your monthly fixed costs by expected monthly lot volume to get a rough per-lot allocation, and revisit it as volume grows — fixed costs shrink per lot as volume scales, which is one reason larger rebate books can afford tighter margins per trade.

How much should you actually keep per lot?

There is no universal safe number — a sustainable margin is one that survives a slow month, a rate cut from the broker, and normal operating costs, not one that only works at your best-case volume. A common approach is to build in a floor: decide the minimum per-lot margin you need to break even at your worst realistic monthly volume (not your average), then price the trader payout so you clear that floor even in a down month. Treat any number a broker or IB program quotes you as an example of how to think about the math, not a promise of what you personally will earn — actual payouts depend on your client volume, retention, and the broker's own terms, which change.

Worked example: three volume scenarios

The table below illustrates the mechanics with a hypothetical broker paying a tiered rate on EUR/USD-equivalent standard lots. These figures are illustrative only — always confirm your actual broker's current rate card and tier thresholds before pricing a payout.

Notice two things. First, the rate you can afford to pay traders rises with volume — a rebate book that only ever hits 50 lots a month cannot sustainably match the trader payout of a book doing 800 lots, even quoting the same broker. Second, fixed-cost allocation per lot drops sharply as volume grows, which is a large share of why the net margin per lot nearly triples between the low and high tiers, not just the broker rate improving.

Where the math breaks: costs people forget

A few line items get left out of rebate math more often than they should:

• Swap and overnight costs. If your rebate structure or client base leans on carry-style or swing positions, factor in how overnight-fee-swap charges interact with your rebate — some brokers reduce rebate eligibility on swap-free or Islamic accounts, which changes your effective per-lot revenue for that segment.
• Clawback clauses. Many broker agreements let the broker reclaim rebates already paid if a client's trading pattern looks like arbitrage, hedging solely to farm rebates, or otherwise violates the program's fair-use terms. A clawback that lands after you've already paid the trader is a real loss, not a paper one — model it as a cost, not a remote risk.
• Minimum-trading-volume and minimum-pip-profit thresholds. Some programs only pay on trades that clear a minimum pip move or hold time, which filters out scalping activity. If your client base scalps, your realized rebate volume can be materially lower than raw lot volume suggests.
• Notional-volume vs. lot count. A handful of brokers calculate rebates against notional exposure rather than a flat per-standard-lot rate, particularly on indices, commodities, or crypto CFDs — confirm which basis applies before you assume a lot-based formula transfers directly.
• Self-rebate exposure. If you or connected accounts trade under your own IB link, understand how the broker treats that volume — some exclude it from tier calculations or flag it during audits, which can distort your reported numbers.

A short checklist before you set your trader payout rate

1. Confirm the broker's current tiered rate card in writing, including exact thresholds.
2. Estimate your realistic monthly volume at a conservative (not best-case) scenario.
3. Calculate your fixed cost allocation per lot at that conservative volume.
4. Set your trader payout so the resulting margin clears your break-even floor.
5. Re-run the calculation whenever volume, broker rates, or your cost base changes materially — quarterly at minimum.
6. Confirm how reporting works so you can verify the broker's paid volume matches what you calculate; see brokers with transparent, real-time rebate reporting for what good reporting looks like in practice.

Choosing between broker offers on the math alone

Two brokers quoting the same headline rebate rate are not equivalent partners once you run the full formula. The broker whose tier thresholds you can realistically reach, whose reporting lets you verify volume without a manual reconciliation, and whose payout terms don't hide clawback conditions in a lightly-read agreement is worth more than a marginally higher advertised rate. If you're building or evaluating a rebate offer from scratch, the rebate IB model explained covers how the whole business fits together, and how to choose a broker for a rebate business walks through partner selection criteria beyond rate alone.

This math also matters if you eventually run more than one broker relationship — comparing per-lot margins across partners is exactly how building a multi-broker rebate comparison site approaches partner selection, and it's the same reason payout cadence matters: a technically higher rate paid monthly can be worth less to your cash flow than a slightly lower rate paid instantly — see instant vs weekly vs monthly rebates for that trade-off. For a broader view of how rebate deals compare to CPA and revenue-share structures across the whole IB market, CPA vs RevShare vs Hybrid: the complete IB commission model guide is a useful reference point.

The partner bridge

Once you have a target per-lot margin and a realistic volume estimate, the next step is comparing actual broker rate cards side by side rather than working from memory or old quotes. Revenika's forex partner program comparison lets you review rebate structures, tier thresholds, and reporting quality across brokers in one place before you commit your trader-facing rate to any single partner.

Frequently Asked Questions

How do I convert mixed lot sizes into standard-lot rebate volume?

Sum every trade's lot size in standard-lot terms — a 0.10-lot trade counts as 0.10 of a standard lot, a 2.5-lot trade counts as 2.5. Most broker back-office reporting does this conversion automatically; if yours doesn't, build the conversion into your own tracking so your calculated volume matches what the broker reports, and treat any mismatch as a signal to double-check terms.

Should I match a competitor's advertised trader payout rate?

Only if your broker relationship and volume support the same margin. Competitors advertising a rate you cannot sustainably match at your current volume tier are either operating at higher volume, accepting thinner margins, or absorbing losses temporarily to acquire clients — none of which you should assume about your own book without doing the math yourself.

Does a higher headline rebate rate always mean a better broker?

No. A broker's headline rate matters less than the tier thresholds required to reach it, how clawback and minimum-volume clauses are written, and whether reporting lets you verify paid volume against your own records. A lower advertised rate with clean reporting and no clawback surprises is often the better business decision.

How often should I recalculate my margin?

At minimum quarterly, and immediately whenever a broker changes its rate card, your client volume shifts materially, or your fixed costs change (new tooling, added support headcount, or a marketing spend increase). Rebate agreements are not static — rates and terms do change, sometimes with limited notice.

Conclusion

Per-lot rebate math is not complicated arithmetic, but it only works when every input is realistic: the broker's actual current tier you qualify for, a conservative volume estimate, your true fixed costs, and the clawback and minimum-volume conditions that can quietly erode paid rebates after the fact. Run the formula before you set a trader-facing rate, rebuild it whenever your volume or broker terms change, and treat any quoted rate as an example to verify rather than a guarantee to build a business plan around.