You've passed one challenge. Now you have three more accounts at two firms, the same strategy, and no intention of clicking the same trade four times. So you set up a copier, and within a week one of the follower accounts is breached for a rule you never broke on the master.
That's the shape of most copy trading prop firm horror stories. Not "copying is banned", but "copying is fine and the follower failed anyway". Both halves matter: what firms typically permit, and the mechanical ways a copied trade fails a follower account while the master sails through.
One caveat up front, repeated at the end because it matters: we're describing common patterns across many firms. Your contract is the one that counts.
What prop firms commonly allow for copy trading
The permissions cluster into four situations, and the answers differ for each.
Copying between your own accounts at the same firm. Commonly allowed, and often explicitly. You passed with your strategy; running the same strategy on your other accounts at the same firm is the expected use. Some firms cap the number of accounts you can hold or the combined funded balance, so the limit is on account count, not on the copying itself.
Copying between your own accounts at different firms. Usually fine from each firm's point of view, because each firm only sees its own account. The caveat is that some firms have language about coordinated trading across firms, written with cross-firm hedging in mind (opposite positions at two firms to guarantee one payout). Same-direction copying is not that, but read the clause.
Copying other people's signals. This is the one that's frequently banned, and it's the one people assume is fine. Many firms require that the person who passed the evaluation is the person making the trading decisions. A paid signal group piped into your funded account through a copier fails that test, and firms are good at spotting it: identical entries across unrelated accounts at the same second are easy to find in their own data.
Account management. Some firms ban letting anyone else trade your account, and some ban you trading anyone else's. Copy trading from a friend's master into your funded follower is account management with extra steps. Treat it as such.
The short version: mirroring yourself onto yourself is the common allowed case. Anything where the trading decision comes from someone else is where you read the terms twice.
The rules a copied trade trips by accident
Here's where the master passes and the follower doesn't. Each of these is a follower rule being evaluated against a trade that was sized and timed for the master.
Max lot size on the follower
Many firms cap lot size per position, sometimes per symbol, and the cap scales
with account size. Your master is a $200k account with a 20-lot cap on gold;
the follower is a $50k account with a 5-lot cap. Copy a 10-lot XAUUSD entry
with a 1:1 multiplier and the follower has broken a hard rule on its first
trade.
Fix: cap the copied volume on the follower side, independently of the sizing mode. Sizing modes scale; a cap clamps. You want both.
Daily drawdown on a different balance
The daily drawdown rule is a percentage of the follower's balance, not the master's. A 1-lot loss that costs the master 0.5% of a $200k account costs a $50k follower 2%. Three of those in a day and the follower is at 6%, past a common 5% daily limit, while the master is comfortably at 1.5%.
This is the argument for balance-ratio sizing rather than a fixed multiplier: the follower's exposure tracks its own balance, so the percentage move is the same on both sides. It's not perfect (different brokers, different spreads, different contract sizes) but it removes the worst of the mismatch.
Consistency rules
Some firms have a consistency rule: no single day may account for more than a set share of total profit. Copying doesn't create this problem, but it doesn't spare you either. If the follower had a skipped trade or a worse fill on the master's best day, its ratio differs from the master's, in either direction. Compute it per account.
News windows
Many firms prohibit opening or closing positions within a window around high-impact news, commonly a few minutes each side. The master opens a trade at 14:29:50 before a 14:30 release, well inside the master's rules (or maybe the master isn't a prop account at all and has no such rule). The copier fills the follower a second later. The follower's firm sees an entry inside its window.
The copier did exactly what you told it to. The rule is on the follower, and the follower's firm doesn't care where the signal came from.
The technical rules that decide whether it works at all
Rules aside, three plumbing problems stop copy trades between prop firm accounts before any rule is involved.
Symbol names differ. Firm A's broker calls it XAUUSD, firm B's calls it
XAUUSD.pro or GOLD. A copier that matches names literally will skip every
gold trade, silently, and you'll notice when the master is up 3% and the
follower is flat. Map the symbols explicitly, and check the
contract size
matches too. A 100-ounce gold contract copied 1:1 onto a 10-ounce one is a
tenth of the exposure you think you have.
Balances differ. Covered above: use balance-ratio sizing and put a per-trade lot cap on top.
The follower needs the master password. A copier has to place orders on the follower, and the investor password can't. On MetaKit that means the follower must be on a full slot; a read-only slot can't be a follower, and the API will refuse the copier. The master can be read-only, since it's only being watched. The investor vs master password post covers what each one can and can't do.
Setting the copier up for a funded follower
The setup post walks through the API end to end. Here's the shape of a copier configured for a prop firm follower, with each setting chosen for one of the rules above.
curl -X POST https://api.metakit.cloud/v1/copiers \
-H "Authorization: Bearer $METAKIT_KEY" \
-H "Content-Type: application/json" \
-d '{
"source_account_id": 3,
"follower_account_id": 5,
"lot_mode": "proportional",
"copy_existing": false,
"symbol_map": { "XAUUSD": "XAUUSD.pro", "US30": "DJ30" },
"filters": { "max_lot": 2, "max_open_positions": 5 }
}'lot_mode: "proportional" scales each trade by the follower/source balance
ratio (that's the balance-ratio mode). filters.max_lot is the clamp that
catches the lot-size rule after scaling. copy_existing: false matters on day
one: you don't want the master's open positions copied at whatever the price
is now, with the follower's daily anchor already set. symbol_map is the
suffix fix; there's also a bulk endpoint, PUT /v1/copiers/{id}/symbol-map,
for when you have twenty of them.
There's no news filter in the copier. If the follower's firm has a news
window, that's on you: set the copier to monitor before the release (it
keeps closing with the master but opens nothing new) and back to on after.
One PATCH each way.
curl -X PATCH https://api.metakit.cloud/v1/copiers/12 \
-H "Authorization: Bearer $METAKIT_KEY" \
-H "Content-Type: application/json" \
-d '{ "state": "monitor" }'Then a separate equity monitor on the follower, sized to the follower's limits and not the master's. Each funded account gets its own drawdown alert; the master's alert tells you nothing about the follower's day.
The full field list for copiers is in the llms.txt reference.
Read your firm's terms
Everything above is "many firms", "a common rule is", "some firms". None of it is your contract. Firms change their rules, sometimes with an email and sometimes without, and two firms with the same headline number (5% daily, say) can measure it from different anchors at different reset times.
Before you point a copier at a funded account, find the clauses on copy trading, account management, third-party signals, lot limits, news windows, and consistency. Read them as the follower's firm will read them, because the follower is the account they're judging.
Then size the copier for the smaller, stricter account. That's the one that fails first.