A Good Faith Estimate (GFE) is a written breakdown of expected charges that any provider must give you before a scheduled service under 45 CFR 149.610 of the No Surprises Act. For hip replacement, this is especially important because the bill comes from multiple sources: the orthopedic surgeon, the anesthesiologist, the hospital or surgery center, and sometimes a separate facility fee. Each of those is a separate bill, and each needs to be captured in your estimate.
The GFE must include the itemized expected charges, the billing codes (CPT codes) for each service, and the provider's name and address. If your final bill exceeds the GFE by more than $400, you have the right to dispute it through the federal patient-provider dispute resolution process. That $400 buffer is not a suggestion. It's a hard legal threshold.
Without a GFE, you're essentially signing a blank check. Hospital chargemasters list hip replacements anywhere from $25,000 to $90,000, and the gap between what they charge and what you owe is determined by negotiations your insurer did years ago. You need to know your number before you book the OR.