Short answer — as of today (16 September 2025) SDB Bank is advertising one of the highest bank fixed‑deposit offers in Sri Lanka: a 5‑year FD with a maturity return of 13%. However, some licensed specialised banks and many licensed finance companies / non‑bank FIs are offering similarly high or even higher rates on specific tenors, so the “most attractive” option depends on the term you want and whether you prefer a commercial/specialised bank or a finance company. (sdb.lk)

Quick details and practical points

• SDB Bank (specialised bank) — 5‑year FD campaign showing a maturity rate of 13% (campaign announced Feb 2025). This is among the highest advertised bank rates for long tenors. (sdb.lk)
• Licensed finance companies and non‑bank FIs (examples: LB Finance, Orient Finance, Assetline) commonly publish higher nominal/AER rates on 1–5 year FDs (examples: LB Finance and Orient/Assetline rate schedules show double‑digit rates on multi‑year tenors). If you compare across institutions you’ll often find the highest nominal returns at finance companies. (lbfinance.lk)
• Deposit protection: the Sri Lanka Deposit Insurance Scheme (SLDIS) currently covers deposits up to Rs. 1,100,000 per depositor per institution — important when placing large sums with smaller banks or finance companies. (cbsl.gov.lk)

What I recommend

• If your priority is the single highest advertised return for a long tenor (and you’re comfortable with the institution), SDB’s 5‑year offer (13%) is one of the top public offers right now. (sdb.lk)
• If you want the absolute highest yield for your chosen tenor, compare published rate tables from: SDB, major specialised banks, and well‑rated finance companies (LB Finance, Assetline, Orient, etc.). Use each institution’s website (or call branches) to confirm current campaign dates and exact effective rates. (lbfinance.lk)
• Check the deposit insurance coverage and the institution’s credit standing (ratings, regulator status) before placing amounts above the insured limit. (cbsl.gov.lk)

If you’d like, I can:

• Compare current 6‑, 12‑ and 36‑month posted FD rates across 6–8 institutions (banks + finance companies) and show the best yields and whether amounts are fully covered by deposit insurance — I’ll fetch the latest published rate pages and list the top offers (I will need to look up live rate pages).