GST Input Service Distributor Credit Allocation Calculator
Reviewed by Finin2min Editorial Desk · Last reviewed 11 August 2026
Allocate common input-service credit among recipient GST registrations in proportion to relevant turnover.
Allocate ISD credit
Credit attributable exclusively to one recipient should be distributed only to that recipient; this tool is for common credit.
Recipient
Turnover
Share
Credit
How This Is Calculated
An Input Service Distributor (ISD) receives invoices for services used across multiple locations of a business and must distribute the credit to the relevant branches, generally in proportion to each recipient branch's turnover relative to total turnover of all recipients — this calculator applies that turnover-ratio distribution.
Frequently Asked Questions
What is an Input Service Distributor (ISD)?
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An ISD is a business office that receives invoices for services used by multiple branches/units of the same entity and distributes the input tax credit to those units, since the actual usage often can't be attributed to just one location.
How is ISD credit distributed among branches?
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Generally in proportion to each recipient branch's turnover relative to the combined turnover of all recipient branches for the relevant period — a branch with a higher share of total turnover gets a proportionately higher share of the distributed credit.
Source and review trail
Use the current official instrument, portal or regulator publication before acting. This panel separates the category authority from page-specific references.
Scope: Computes the distribution of common input tax credit from an Input Service Distributor (ISD) to its recipient units, per the ISD credit-distribution formula under Section 20 of the CGST Act and Rule 39.
Calculation logic
For each type of common input service credit, determine the recipient units eligible to receive a share (those units to which the service is attributable; where attributable to more than one unit, distribution follows the turnover-ratio method described next).
Where the credit relates to more than one recipient unit and is not directly attributable to a single unit, distribute it in the ratio of each unit's turnover (in the relevant state/UT) to the aggregate turnover of all units to which the credit is attributable, for the relevant period (generally the preceding financial year, or a specified quarter if the preceding-year figures are not available), per Rule 39.
For credit attributable to a single specific recipient unit, allocate it entirely to that unit rather than applying the turnover-ratio distribution.
Inputs and assumptions
Turnover-ratio distribution follows the Rule 39 formula and the 'relevant period' definition it prescribes.
ISD registration and distribution has become mandatory (rather than optional) for entities distributing common input service credit across multiple GSTINs under the same PAN, per the amendment applicable from the notified date — the calculator assumes the entity is correctly registered as an ISD where this mode is used.
Exclusions and edge cases
Does not itself distribute credit for common input goods (as distinct from input services) — the ISD mechanism under Section 20 is specifically for input services, not goods, which the calculator's scope reflects.
Cross-charge (an alternative mechanism, distinct from ISD, for distributing costs of internally generated/procured common services between distinct persons under the same PAN) is a separate concept not computed by this ISD-specific allocator.