Sri Lanka provisional tax via Advance Income Tax (AIT) quarterly instalments under s 90 of the Inland Revenue Act — who pays, calculation, due dates and penalties.
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Every figure is drawn from this Tax Guide and cited to its source.
Companies (all CIT payers)
All resident companies with a CIT liability are required to pay quarterly AIT instalments under s 90 of the IRA. Also applies to non-resident companies with a Sri Lanka tax liability.IRA s 90
Individuals with business income
Self-employed individuals and individuals with business income (not fully covered by APIT withholding) must make quarterly instalment payments.IRA s 90; IRD AIT Individual Guidance
Basis of calculation
Instalments are calculated based on: (a) the prior year's assessed tax liability (most common method), OR (b) an estimate of the current year's income tax liability. Companies may choose whichever is appropriate.IRA s 90
Exclusions from AIT base
Gains from realisation of investment assets (capital gains) are excluded from the AIT instalment calculation base.IRA s 90
Q1 instalment
Due by 15 July (for Y/A 1 April–31 March)IRA s 90; IRD AIT Payment Schedule
Q2 instalment
Due by 15 OctoberIRA s 90; IRD AIT Payment Schedule
Q3 instalment
Due by 15 JanuaryIRA s 90; IRD AIT Payment Schedule
Q4 instalment (balance)
Due by 15 April (after year-end). Final balance of tax (after deducting all AIT instalments and WHT credits) due with the annual return by 30 November.IRA s 90; IRD AIT Payment Schedule
Penalty for underpaid instalments
10% penalty on the underpaid or unpaid AIT instalment amount.IRA s 90; IRD AIT Penalty Notice
Credit against final tax
AIT instalments paid are credited against the final CIT liability assessed at year-end. Excess AIT (overpayment) may be refunded or carried forward.IRA s 90; IRD Return Processing Guidance
WHT credit
Withholding taxes deducted from income received (e.g. AIT on dividends, interest) are also credited against the final CIT/personal income tax liability.IRA s 90B; First Schedule; IRD AIT/WHT Credit Guidance
Payment method
Via RAMIS (IRD online portal) or through authorised banking channels.IRD RAMIS – www.ird.gov.lk
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Other Sri Lanka computations in the OpenAccountants Tax Library.