By Scalpel Team. . 9 min read.
In short
For a scalper who buys and sells with marketable orders, IBKR Pro Fixed ($0.005 a share, $1.00 minimum, exchange and clearing fees included) is usually cheaper than Tiered on orders above about 150 shares, because Tiered's $0.0035 a share plus about $0.0032 of exchange and clearing fees comes to roughly $0.0067. Tiered wins on small orders, on orders that rest and earn exchange rebates, and once your monthly volume passes 3 million shares. IBKR Lite is not an option for API trading.
Commissions are the one cost a scalper pays on every trade, win or lose. On IBKR you pick between two IBKR Pro plans for US stocks, Fixed and Tiered, and the cheaper one depends on how you trade: share size, price, how many round trips, and whether your orders take liquidity or add it. This post puts IBKR's current numbers into worked tables so you can see which way your own trading falls.
Scalpel is independent and not affiliated with or endorsed by Interactive Brokers.
From IBKR's US stock commissions page, checked on October 15, 2026:
| IBKR Pro Fixed | IBKR Pro Tiered | |
|---|---|---|
| Per share | $0.005 | $0.0035 up to 300,000 shares a month, then lower |
| Minimum per order | $1.00 | $0.35 |
| Maximum per order | 1% of trade value | 1% of trade value |
| Exchange fees | Included | Added (or a rebate, see below) |
| Clearing fees | Included | Added: $0.0002 a share |
| Pass-through fees | Included | Added: 0.0735% of the commission |
| Regulatory fees | Added | Added |
Tiered's per-share rate steps down with your monthly US and Canadian share volume, applied on the shares above each break:
| Monthly shares | Tiered rate |
|---|---|
| 300,000 or fewer | $0.0035 |
| 300,001 to 3,000,000 | $0.0020 |
| 3,000,001 to 20,000,000 | $0.0015 |
| 20,000,001 to 100,000,000 | $0.0010 |
| Over 100,000,000 | $0.0005 |
The regulatory fees apply on both plans and are tiny on a scalp: the SEC fee of $0.0000206 times the value of each sale (about 4 cents on a $2,000 sell) and the CAT fee of $0.000003 a share. IBKR's page shows FINRA's trading activity fee at zero under a fee holiday from October 1 to December 31, 2026.
On Tiered you pay the venue's own fee, and that depends on whether your order takes liquidity or adds it:
IBKR's Nasdaq fee table for stocks at $1.00 and up lists $0.0030 a share to remove liquidity and a $0.0013 rebate to add it. NYSE Arca's table lists the same $0.0030 to remove and a $0.0020 rebate to add, for Nasdaq and NYSE-listed stocks. Under $1.00 the removal fee becomes 0.30% of the trade's value and the add rebate drops to zero in regular hours.
Two notes from IBKR's own page are worth reading twice. IBKR "typically will not directly pass" enhanced rebates it earns at high volume, so assume the published rebate at best. And it warns traders to understand "the ECN charges for removing liquidity when sending marketable orders for low priced stocks (under USD 2.50)," which is most of the small-cap momentum universe.
Here is a single buy that takes liquidity, at the $0.0035 tier, using the Nasdaq fees above:
| Item | 1,000 shares at $2 on Tiered | 1,000 at $2 on Fixed | 300 shares at $10 on Tiered | 300 at $10 on Fixed |
|---|---|---|---|---|
| Commission | $3.50 | $5.00 | $1.05 | $1.50 |
| Exchange fee (remove) | $3.00 | Included | $0.90 | Included |
| Clearing | $0.20 | Included | $0.06 | Included |
| Pass-through and CAT | $0.01 | $0.00 | $0.00 | $0.00 |
| Buy total | $6.71 | $5.00 | $2.01 | $1.50 |
| Sell total (adds the SEC fee) | $6.75 | $5.04 | $2.07 | $1.56 |
| Round trip | $13.45 | $10.05 | $4.09 | $3.06 |
Per share, a taking order costs about $0.0067 on Tiered against $0.005 on Fixed. At the next tier down ($0.0020) Tiered is still about $0.0052. Only above 3 million shares a month ($0.0015) does a taking order on Tiered drop under Fixed.
Now the same trades repeated through a day. "Both take" is the usual scalping pattern. "Sell adds" assumes you buy at the ask and sell resting at the ask (a limit target). "Both add" is a trader who works bids and offers and gets the Nasdaq rebate on both sides.
1,000 shares at $2, cost per day:
| Round trips a day | Fixed | Tiered, both take | Tiered, sell adds | Tiered, both add |
|---|---|---|---|---|
| 5 | $50.24 | $67.26 | $45.76 | $24.26 |
| 20 | $200.94 | $269.05 | $183.05 | $97.05 |
| 50 | $502.36 | $672.62 | $457.62 | $242.62 |
300 shares at $10, cost per day:
| Round trips a day | Fixed | Tiered, both take | Tiered, sell adds | Tiered, both add |
|---|---|---|---|---|
| 5 | $15.32 | $20.43 | $13.98 | $7.53 |
| 20 | $61.27 | $81.70 | $55.90 | $30.10 |
| 50 | $153.18 | $204.26 | $139.76 | $75.26 |
These use the $0.0035 tier for every share. Over a month the busier rows move into cheaper tiers, so here is the same "both take" pattern over 21 sessions with the tiers applied as volume builds:
| Pattern, 21 sessions | Shares in the month | Fixed | Tiered, both take |
|---|---|---|---|
| 1,000 at $2, 5 a day | 210,000 | $1,055 | $1,412 |
| 1,000 at $2, 20 a day | 840,000 | $4,220 | $4,839 |
| 1,000 at $2, 50 a day | 2,100,000 | $10,550 | $11,423 |
| 300 at $10, 5 a day | 63,000 | $322 | $429 |
| 300 at $10, 20 a day | 252,000 | $1,287 | $1,716 |
| 300 at $10, 50 a day | 630,000 | $3,217 | $3,794 |
The gap narrows with volume but Fixed stays cheaper for a pure taker at these sizes. If even one side of your trade adds liquidity, Tiered pulls ahead. These are estimates from the published rates; your statement is the real number, and venue fees differ by exchange and by session.
The per-order minimums and the 1% maximum change the picture at the edges.
Small share counts favor Tiered. Fixed charges at least $1.00 an order. Tiered's minimum is $0.35, plus the venue fee:
| One buy that takes liquidity | Tiered | Fixed |
|---|---|---|
| 50 shares at $10 | $0.51 | $1.00 |
| 100 shares at $5 | $0.67 | $1.00 |
| 150 shares at $5 | $1.01 | $1.00 |
| 200 shares at $5 | $1.34 | $1.00 |
The crossover sits at about 150 shares for stocks over $1. If you scale out in 50 and 100-share pieces, each piece pays its own minimum, and Fixed charges a full dollar for each.
The 1% cap protects sub-dollar orders. On both plans the commission cannot exceed 1% of the trade's value, and IBKR applies the cap even when it is below the minimum. IBKR's own examples: 1,000 shares at $0.25 costs $2.50 on Fixed (the cap, not $5.00), and 10 shares at $0.20 costs $0.02. Two catches:
So on sub-dollar stocks the two plans land close together, and the venue fee, not the commission, is the big number. Orders where the cap applies also do not count toward Tiered's volume tiers.
Modified and partial orders. IBKR treats a modified order as a cancel and a new order. Its example: 200 shares submitted, 100 fill, you modify, and the next 100 fill: two minimums. An order that stays open overnight is also a new order for minimums.
IBKR Lite charges $0 commission on US exchange-listed stocks, but it does not work with the API. IBKR's third-party platform FAQ says you need a funded IBKR Pro account, and that the message "API support is not available" means you have an IBKR Lite account or your switch to Pro has not taken effect yet. If you trade through TWS hotkeys alone, Lite is a choice; if you use any API tool, it is Pro Fixed or Pro Tiered. IBKR's page also says directed API orders cannot use Tiered, while SmartRouted API orders can use either plan.
To switch, in Client Portal open the user menu and go to Settings > Account Configuration > IBKR Pricing Plan, then pick Fixed or Tiered under IBKR Pro. IBKR's pricing plan guide says requests are processed no later than the Friday after you make them.
The cheapest way to decide is to look at your own last month: export your trades, count the orders under 150 shares and the fills that added liquidity, and price them both ways. For the bigger picture, see scalping on Interactive Brokers and the full day trading on Interactive Brokers setup.
Scalpel trades through your IBKR Pro account over the API, and every LIVE order uses SMART routing, so it works with either plan. In LIVE it books the commission IBKR reports for each fill, so the FEE column and your P&L show your real plan's cost.
In SIM, the plan is a setting. Open Settings > Risk > Commission plan and pick IBKR Pro Tiered (the default) or IBKR Pro Fixed. On Tiered, SIM adds the $0.003 exchange fee on fills that take liquidity and $0.0002 clearing on every fill, so the 1,000-share round trip above shows about $13.40 in SIM. SIM leaves out the regulatory fees and does not pay rebates, so on a Tiered account that rests orders your real bill will come in a little lower. The commissions guide has the details and a Custom option for your own tier.
Practicing in SIM on the plan you are really on is the honest way to see whether a small edge survives its fees. A 10-cent scalp on 300 shares grosses $30; at $4.09 a round trip, Tiered taking both sides keeps about $25.91 of it.
Fees checked on October 15, 2026.
Trading carries a significant risk of loss. Nothing here is financial advice.