Short answer — for longer tenors (around 5 years) SDB Bank has been advertising one of the highest bank fixed‑Deposit offers in Sri Lanka (a special 5‑year FD campaign with a maturity rate of about 13%). Several licensed finance companies and specialised banks are also offering very competitive (and in some tenors higher) yields, so the “most attractive” depends on the tenor, amount and whether you prefer a Commercial Bank vs a finance company. (Asianmirror.lk)

Quick details and things to check (so you can pick the best option for your needs)

• SDB Bank: 5‑year FD campaign showing a maturity return around 13% (campaign reported in 2025). Good if you want a high long‑term bank FD. (Asianmirror.lk)
• Finance companies / specialised banks: some (e.g., Assetline, Janashakthi Finance and others) publish higher rates for specific tenors — you’ll commonly see stronger yields on 1–3 year and multi‑year terms with these institutions. Compare their published rate tables for the exact tenors you want. (assetlinefinance.lk)
• Comparison tools: aggregator/comparison sites list current rates across banks and finance companies — useful to compare tenors and effective annual yields quickly. (Deposit.lk)

Safety & practical checks before you commit

1. Deposit insurance: confirm eligibility and the maximum cover (Sri Lanka’s Deposit Insurance Scheme currently has a cap — check each product’s insurance status).
2. Tenor and payout method: maturity vs monthly interest, reinvestment rules, penalties for early withdrawal.
3. Promotion vs regular rate: some high rates are time‑limited campaigns — confirm the rate is currently available and for your Deposit size. (Asianmirror.lk)
4. Institution type: licensed commercial banks generally have broader regulatory oversight; finance companies can offer higher yields but can carry different risk/terms — check credit standing and disclosures. (assetlinefinance.lk)

If you want, I can:

• Pull the current published FD rates for a specific tenor (e.g., 1 year, 3 years, 5 years) across the major banks and finance companies and show a short ranked list (I’ll check the live rate pages and include citations).