It depends on how bad, how recent, and why. Lenders look at patterns. A single old collection from years ago is very different from multiple recent late payments. What matters most is recent behavior. The last 12–24 months tell the story. I’ve seen buyers denied because of assumptions — not because they were actually unqualifiable. Sometimes small strategic steps can significantly improve approval strength. Credit problems are not always permanent roadblocks. But they do require strategy.
Please consult your Mortgage Advisor for guidance specific to your situation before making changes.