Another reason you could be denied a mortgage might have to do with your income. You'll use the money in checking for bills, but will also likely be able to access it easily by taking cash out of an ATM or by using your debit card to charge purchases.If you have your savings intermingled with the money you're using for your expenses, it can be too hard to keep track of what is meant to be reserved and what's left to spend.For example, if you have $8,200 in your account but $5,500 is supposed to be saved, you'd have to subtract $5,500 from $8,200 to see what was left over to use for your expenses. Especially since the whole point of shopping at Costco is to save you money by scoring bargains with your membership, not to leave you with a huge credit card bill because you just can't say no to its tasty treats or unique household items.You can avoid a Costco visit by shopping online for the things you really need, using grocery pickup, or simply shopping somewhere else where you aren't as likely to find tempting products you don't need.2.