Before you start

Passport with a valid long-stay extension
A Cambodian phone number for OTPs
Proof of address — a lease or a Commune/Sangkat letter
A small cash opening deposit

Step-by-step

1
Pick ABA or ACLEDA for coverage
ABA has the app most foreign residents end up using and a good Siem Reap branch network. ACLEDA has the widest reach if you travel into the provinces, which matters more here than in the capital. Both offer dual USD and riel accounts under one customer number, which is what you want.
In personWho: YouAn hourSmall opening deposit
2
Bring more documents than you think you need
Siem Reap branches process fewer foreign applications than Phnom Penh ones and tend to apply the checklist literally. Take the passport, the visa extension page, the lease, the Sangkat letter and an employer letter if you have one. It is a shorter trip than coming back.
In personWho: You~1 hourFree to open
3
Activate the app and generate your KHQR
Install the bank's app, complete the OTP with your Cambodian SIM and generate your personal KHQR code. That single QR is the national interoperable standard — anyone on any Cambodian bank app can pay it, and you can scan any merchant's.
Mobile appWho: You~20 minFree
4
Get used to riel for small money
ATMs mostly give USD 100 notes or riel, and the small dollar bills that used to circulate have largely gone. Anything under about ten dollars is settled in riel across Cambodia. Withdraw riel for daily life and keep dollars for rent and school fees.
In personWho: YouOngoingOwn-bank ATM withdrawals usually free
5
Plan for seasonal income if you work in tourism
Hospitality and tour work in Siem Reap is heavily seasonal, and the wet-season trough is real. Keep several months of expenses in the account rather than in cash, and be wary of building a life on high-season earnings alone.
Mobile appWho: YouOngoingFree

Documents you’ll need

Passport with visa extension
Cambodian SIM / phone number
Lease or Commune/Sangkat residence letter
Employer letter, if you have one
Cash opening deposit

Things most newcomers don’t know

KHQR works in Siem Reap exactly as it does in the capital — including at market stalls.

The National Bank of Cambodia's KHQR is a single interoperable standard: one code, any participating bank's app. In a town with a large informal economy that means you can pay a tuk-tuk driver, a market vendor or a guesthouse from your phone. Combined with instant free Bakong transfers, it removes most of the reason to carry cash.

Source: National Bank of Cambodia / Bakong

Provincial branches apply the checklist more literally than Phnom Penh ones.

Head-office branches in the capital see foreign customers constantly and exercise judgement; a Siem Reap branch may not. The practical answer is not to argue but to over-prepare — bring the lease, the Sangkat letter and an employer letter even when the website says one of them will do. Failing that, opening an account on a Phnom Penh trip and using it here works fine.

Source: community-reported

Take riel out of the ATM, not dollars.

Under the National Bank's de-dollarisation programme small US bills have been withdrawn from circulation, and ATMs dispensing dollars now typically give hundreds. A hundred-dollar note is useless at Phsar Leu. Withdraw riel for everyday spending and reserve dollars for rent, deposits and anything above about fifty dollars.

Source: National Bank of Cambodia; Cambodianess on de-dollarisation

Seasonality is a banking problem, not just an income one.

Siem Reap's economy contracts sharply from May to October. Foreign residents who work in tourism routinely underestimate how thin the low season is, and a dormant account with no incoming transfers can be flagged or frozen. Keep the account active with small regular transactions, and keep a buffer that covers the trough.

Source: community-reported