What is being looked at is new debt. Are those new balances or accounts going to effect your ratios? Then you could be looking at change in your qualifications.
Great advice is to discuss this ASAP with your loan officer as this could be a potential problem especially if you are tight on your ratios.
What they are looking for are new accounts and increases in balances and, in some cases, current late payments.
Yes, the lender will pull your credit report at least once, maybe twice just before closing and yes, if this isn't fixed there will be a big problem.
Best to get it corrected now if possible.
Why did it drop? That is a huge issue and a large drop. Generally, Realtors and Lenders warn buyers not to do anything that will change their credit.
My best advice is to pin down the cause of the point drop and arrange swift payment to that creditor you owe money to...then you can get a rapid re-score.
Yes....... they will check your credit prior to closing, and yes, it may affect your loan..........weren't you advised not to do anything that could change your credit scores? No big purchases........no late payments..............nothing !
Get on the phone tomorrow and call your mortgage rep and agent.......