Good question, and you’ll almost certainly be OK with only a small, temporary change in your credit scores. First and foremost, credit bureaus view multiple mortgage related credit inquiries within a 30 day period as one inquiry, as opposed to multiple credit card inquiries. Many folks applying for mortgages do have multiple lenders pull their credit, and lenders also may have to repull credit during the loan process. Because the HELOC application is also mortgage related, it’s likely that all three inquiries will be viewed as one to the credit scoring models. Even if they weren’t, however, any impact to your scores would be minor and fleeting, perhaps 5 points or so. If anything, you may want to apply for the heloc sooner rather than later so it will be more likely within the 30 day window, but you should be fine regardless.