Detracting the Khums of Previous Year from the benefits of following year is not Permissible
Issue No. 1584- If a person enters a deal with the Mujtahid or his representative about khums and it is agreed that he pays the due khums in the following year, he cannot deduct khums from the incomes of that year. For example, if he owes £200.00 as khums, and in the following year, he has £2000.00 more than the expenses of his year, he should pay khums of the £2000.00 together with £200.00.