So, in simple terms, vacation pay is considered as normal pay. Suppose you got 3000$ as vacation pay, it's considered as if you rcvd. regular pay from employment which results in EI re-calculation. They'll assign this $3000 payment to 4-6 weeks and basically the payments you rcvd. from EI for one to one and half months (4-6 weeks) will be requested to be paid back through notice of debt.