Modvat credit rules updated to limit simultaneous claims and require duty documents before claiming credit.

Amendments clarify Modvat credit: Rule 56A now bars simultaneous credit under Rules 56A and 57A for the same inputs but allows proforma credit for non Modvat inputs; Rule 57E permits adjustment whenever input duty varies; Rule 57G requires prescribed duty paying documents before credit though inputs may be used with RG 23A entry pending documents; Rule 57H allows transitional credit for inputs in stock at acknowledgement or received after declaration filing but excludes inputs used for exempt goods.

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