Deposit return estimate
Sri Lanka Fixed Deposit Calculator – Interest, Maturity & WHT/AIT
Calculate gross fixed-deposit interest, estimated withholding or Advance Income Tax, net returns and maturity value using a rate and payment method from your Sri Lankan bank or finance company.
Fixed deposit interest calculator
Estimate your deposit return after AIT
Use the annual rate shown in the institution’s quotation. The calculator does not assume that an advertised bank rate is still current.
Estimated deposit return
Interest paid at maturity
- Average gross monthly interest
- —
- Average net monthly interest
- —
- Annualized net return for this estimate
- —
- Deposit period
- —
Interest methods
Maturity, monthly payout and reinvestment calculations
The maturity and monthly-payout options use proportional simple interest: principal × annual rate × months ÷ 12. Monthly reinvestment credits interest every month and earns later interest on the amount retained after any selected AIT deduction.
Banks can use daily calculations, product-specific effective rates, early-withdrawal rates and different credit dates. Compare this result with the written quotation and account terms before investing.
The 10% AIT setting is not always your final income tax
Sri Lanka’s Inland Revenue Department requires 10% AIT on applicable Sri Lankan-source interest from 1 April 2025. Certain resident individuals whose assessable income from all sources does not exceed the applicable threshold may use the official self-declaration process. Eligibility and final tax treatment depend on the depositor’s full circumstances.
Common fixed-deposit questions
How is monthly fixed-deposit interest estimated?
For the non-reinvested monthly option, estimated gross monthly interest is the deposit multiplied by the annual nominal rate and divided by 12. The institution’s actual credit date, day-count convention and quoted monthly rate remain authoritative.
Does the highest advertised rate always give the best return?
Not necessarily. Compare the term, payout method, early-withdrawal conditions, tax treatment and the institution accepting the deposit. A maturity rate and a monthly-payout rate may not be directly interchangeable.