Bank Guarantee Commission for issuing letter of guarantee is calculated on the basis of difference between the original letter of guarantee and cash deposit given to the bank as security in relation to duration of the guarantee. Commission for extending a letter of guarantee is tantamount to commission for issuing it. If the amount of guarantee is reduced, the commission could be reimbursed in proportion to reduction in guarantee and remaining time of bank guarantee before maturity, after deducing one month in favor of the bank.