@rapid-account-67960 You don’t actually have to classify anything.
• Just look at your monthly grocery spend last year around Pesach and compare that to your standard.
• For example, if in April you spent 2000 NIS more, then you just divide 2000/12 and allocate that much towards the Pesach fund each month.
• When Pesach arrives, do the same.
◦ All groceries up to your standard amount get assigned to the regular grocery category.
◦ Anything above that goes to the Pesach category.
(BTW - I do this with all my yom tov expenses in a single category, so I include 4 minim, yamim noraim seats, sukka touch up expenses, shalach manos, etc., as well as additional groceries, then divide that by 12 and allocate monthly.)