Sri Lanka Recurring Deposit (RD) Calculator

A Recurring Deposit is an annuity-immediate: a fixed monthly contribution made at the end of each month, with interest credited and compounded at a regular frequency until maturity. Every Sri Lankan bank — BOC, People's Bank, NSB, HNB, NDB, Commercial Bank, Sampath, NTB, Seylan, DFCC — uses the same closed-form formula to advertise its RD products. This calculator applies that formula exactly and layers on the Inland Revenue Department's Withholding Tax treatment so you see the take-home maturity rather than the brochure number.

The maturity formula (monthly compounding)

For end-of-month deposits compounded monthly at the bank's nominal annual rate r:

  i  = r / 12               // monthly rate
  M  = P × [((1 + i)^N − 1) / i]
  Interest = M − P × N
  WHT      = 5% × Interest   // resident, not senior
  Net      = M − WHT

Where P is the monthly deposit, N is the tenure in months, and M is the gross maturity. The bracketed term is the future-value annuity factor — identical to the one CBSL uses in its published worked examples and to the spreadsheets every bank distributes to branch staff.

Quarterly compounding (some private banks)

A handful of private banks credit RD interest quarterly rather than monthly. In that case three monthly deposits within a quarter accrue simple interest at the monthly rate r/12 for 2, 1, and 0 months respectively; the resulting quarter-end balance then compounds at i_q = r/4 between quarters. For a tenure N that is divisible by 3, the closed form collapses to M = P × (3 + i_q) × [((1 + i_q)^Q − 1) / i_q] where Q = N/3. Quarterly compounding produces a lower maturity than monthly for the same nominal rate; if a bank quotes the same headline rate for both, the monthly variant always wins.

Withholding tax and the senior-citizen exemption

Under Section 84 of the Inland Revenue Act No. 24 of 2017 (as amended by Act No. 04 of 2025), banks deduct 5% WHT on the interest credited to a resident individual's RD/FD/savings account. The deduction is made at the time of credit and remitted to the IRD by the bank — you do not need to file anything separately unless you cross into the income-tax brackets and need to reconcile the WHT against your APIT/SET liability.

Senior residents (60 years and above) are exempt from WHT on aggregate interest from financial institutions up to Rs 1,500,000 per Year of Assessment. The calculator annualises your RD's interest (gross interest ÷ years of tenure), adds the "other annual interest income" you enter, and compares the combined figure to the Rs 1.5 million ceiling. Below the ceiling, WHT is zero. Above it, WHT applies pro-rata on the excess so the saving is progressive rather than cliff-edged.

What the calculator does not include

Premature withdrawal penalties (typically 1% rate reduction per year of shortfall, bank-specific) are out of scope — open a related case with your bank for the exact figure. Foreign-currency RDs and non-resident (FCBU/NRFC) products are taxed under different sections of the Inland Revenue Act and are not modelled here. Joint-account WHT apportionment between two depositors' tax returns is handled at income-tax filing time, not by the bank's payroll system; the calculator shows the bank-deducted gross WHT. Inflation adjustment, currency-risk hedging, and side-by-side multi-bank comparison views are planned for v2.

Deposit insurance — how safe is your RD?

Deposits at licensed commercial banks are insured up to Rs 1,100,000 per depositor per bank by the CBSL Deposit Insurance and Liquidity Support Scheme (Amendment Regulations 2023). NSB deposits are guaranteed in full by the Government of Sri Lanka under the National Savings Bank Act No. 30 of 1971 — no cap. If your projected maturity at a single LCB will exceed Rs 1.1 million, splitting the monthly amount across two banks (or directing the bulk through NSB) keeps every rupee under the insurance umbrella. The calculator flashes a reminder once you cross the cap on the screen above.

Three scenarios reconciled rupee-for-rupee against the implementation. Plug each set of inputs into the calculator above — the maturity figures should match to the rupee.

• Central Bank of Sri Lanka — Statistical Tables (Deposit Interest Rates of Commercial Banks)
• Inland Revenue Act No. 24 of 2017 — Section 84 (WHT on interest)
• Inland Revenue (Amendment) Act No. 04 of 2025 — senior-citizen ceiling
• CBSL Deposit Insurance & Liquidity Support Scheme (Amendment) Regulations 2023
• National Savings Bank — RD product page (Sthree, Hapan)

Formulas, WHT rate, and the senior-citizen exemption ceiling were last cross-checked against the sources above on 2026-05-17. The page is reviewed every April (start of new SL Y/A) and within 48 hours of any new Inland Revenue Amendment Act. Bank-specific rates shift continuously and are not auto-fetched — type the rate from your bank's most recent leaflet.

Comparison savings rate of 4% is taken from the lower end of CBSL's Average Weighted Deposit Rate (AWDR) savings band published in the monthly Statistical Tables.