IBKR Tiered vs Fixed: the published rates cannot decide it, and below 200 shares they are not the point

Fixed is all-inclusive at $0.005 a share, Tiered is $0.0035 plus pass-through fees nobody can quote in advance. What the published numbers do settle is that under 200 shares the minimum charge, not the rate, is what you pay.

Last verified 1 September 2026 · how we check

This is the question people ask after opening an IBKR Pro account, and most answers to it are made up. The honest version has two halves: what the published rates settle, and what they cannot settle at all.

The published rates

Fixed is described as all-inclusive: exchange, clearing and regulatory fees are covered by that half-cent. Tiered quotes the lower rate and adds those fees separately. So the 30% gap between $0.005 and $0.0035 is not a discount, it is the price of unbundling, and the bundle is where the uncertainty lives.

Why nobody can quote you the crossover

To compare the two you need the pass-through total on Tiered, and that number is not a constant. It depends on which venue the order reaches, whether the order adds or removes liquidity, and the exchange’s own fee schedule for that class of security, all of which vary per order. On some venues adding liquidity earns a rebate, so the pass-through can be negative.

That is the real reason the internet’s answer to this question is vague. Anyone who gives you a single break-even share count has quietly assumed a fee they cannot know, and the assumption is doing all the work.

The check that does exist is your own statement. Both plans itemise the components, so running a month on one and reading the fee lines answers for your own order flow what no table can answer in general.

What the rates do settle

The minimums. Both plans charge a floor per order, and below a certain size that floor is the entire story.

Tiered figures are the base rate only, before pass-through fees.

Two thresholds fall out of that, and both are exact:

The Fixed minimum binds up to 200 shares, because $1.00 divided by $0.005 is 200. Below that you are paying the floor, not the rate.

The Tiered minimum binds up to 100 shares, because $0.35 divided by $0.0035 is 100.

On a ten-share order, Fixed costs ten cents a share, twenty times its own headline rate. That is not a criticism of IBKR; every broker with a minimum behaves this way. It is a criticism of comparing brokers by their per-share rate, which is the number that stops applying exactly where small accounts live.

The third plan has no minimum at all

Anyone landing on this comparison because their orders are small is asking the wrong question, because IBKR Lite charges zero commission with no minimum and no maximum. At ten shares, where Fixed effectively costs ten cents a share, Lite costs nothing.

That is not a free lunch, and IBKR says so in its own routing disclosure. Lite orders “are generally routed to select over-the-counter market-makers”, whose agreements “provide Interactive Brokers payment for order flow”, with a stated potential effect of:

reduced price improvement on executions received by IBKR-LITE clients

That sentence is the firm’s, not a critic’s, and we set it out in full on our Interactive Brokers pricing page. Pro routes through SmartRouting instead, which is what the commission buys.

So the real ladder is three rungs, not two. Lite trades commission for routing, and Pro Fixed trades a higher rate for a bundled, predictable bill. Tiered trades predictability for a lower base rate. Choosing among them is a question about what you want to be uncertain about, and only one of the three answers is free.

The 1% cap almost never applies

Both plans cap the commission at 1% of trade value, which sounds protective and is nearly inert. On the Fixed plan the cap only binds when the share price is below one dollar at 100 shares, or below fifty cents at 1,000 shares.

So it protects penny-stock orders and nothing else. On any ordinarily priced share the cap sits far above the commission and never engages.

What actually decides your bill

Commission is rarely the largest number, and this is the point our best day trading platform page makes with the same arithmetic. On a 1,000-share order the whole Fixed commission is $5.00. One cent of price improvement on that order is $10 — twice the commission.

That makes routing worth more than the plan choice at any size where the plan choice is worth arguing about. Routing is disclosed quarterly in the broker’s SEC Rule 606 report, and reading one takes less time than the comparison most people do instead.

Two other lines belong in the total and neither is on the commission page:

Market data. Real-time feeds carry exchange fees at your professional or non-professional status, the same line item we set out for Sierra Chart and TradingView, where professional classification moves the entry price from $12.95 to $199.95 a month for identical software.

Currency conversion, if you fund in one currency and trade in another. It is a separate charge and, for anyone trading US shares from outside the US, frequently larger than the commission on the trade.

How to choose without a fabricated break-even

Under 200 shares an order, take the minimums seriously. Tiered’s $0.35 floor is a third of Fixed’s $1.00, and at those sizes that ratio is the whole comparison, because neither headline rate is in effect.

Above 200 shares, run one month on Fixed and read the statement. You will have your own pass-through numbers, which is the only version of this comparison that is not guesswork.

If your order flow is predictable and large, ask about Tiered’s pass-through on the venues you actually reach, rather than in the abstract. That is a support question with a real answer.

If you place a small number of small orders, neither plan is your problem. The minimum charge is, and the fix is fewer, larger orders rather than a different plan.

What we checked, and what we didn’t

The rates, minimums and caps come from Interactive Brokers’ published US stock commission schedule, read on 1 September 2026. The effective per-share figures, the 200-share and 100-share thresholds and the share-price levels at which the 1% cap binds are our arithmetic on those published numbers.

We hold no IBKR account and have not traded through either plan, so we report no pass-through totals, no fill quality and no routing outcomes of our own. Where this page says the crossover cannot be quoted, that is a statement about how Tiered is constructed, not a gap we expect to fill later.

Sources

• Interactive Brokers: US stock, ETF and warrant commissions
• SEC: Rule 606 order routing disclosures