Short answer: For sheer ease (lowest paperwork + smallest initial deposit), the State Mortgage & Investment Bank (SMIB) and some smaller local banks such as SDB (Sanasa Development Bank) are among the easiest to open a Sri Lankan savings account with — SMIB publishes very low initial-deposit requirements (from LKR 500 / LKR 1,000 for many products) and simple ID rules. Commercial Bank and several private banks (Seylan, Nations Trust, HNB, etc.) are also easy and commonly let you open accounts with small initial deposits and standard ID/address documents — many of them now let you apply through their mobile apps or online so you can open remotely. (smib.lk)

Quick details you’ll usually need

• Primary ID: NIC (for citizens) or passport/driving licence. (combank.lk)
• Proof of address if different from ID (utility bill, bank statement). (sdb.lk)
• Initial deposit: varies by bank (examples: SMIB LKR 500–1,000; Commercial Bank LKR 1,000; Nations Trust / SDB list higher minimums for some products). Check the product page for the exact figure. (smib.lk)

Practical recommendation

• If your only priority is minimum friction and lowest cash to start: check SMIB (very low starter deposit) or SDB. (smib.lk)
• If you want easiest remote/digital opening: look at banks that advertise mobile/app account opening (Nations Trust, Seylan, Commercial Bank and others). These typically let you apply, upload ID and proof online and then visit a branch only if required. (nationstrust.com)

If you want, I can:

• look up the current exact minimum initial deposit and whether full online (no-branch) opening is available for 2–3 banks you care about (I can check SMIB, Commercial Bank, and Nations Trust right now).