Sellers are legally required to disclose any known deficiency to the buyers. Unfortunately, not all parties will agree on exactly what constitutes a deficiency, so your safest bet is to disclose everything that may be considered a flaw.
While it is by no means a complete listing of potential problem areas, this checklist provides a good starting point for identifying possible liability problems in your home.
Disclose the age of the house and any major problems you've experienced (including any you believe have been corrected). Provide a complete list of all known repairs and improvement projects that have been completed. Specify any variances or other zoning actions affecting the property.
Disclose any known problems with the home's heating, plumbing, electrical, and air conditioning systems. List the ages of all furnaces, air-conditioning units, and water heaters. Provide copies of the service records on all systems.
Disclose any known problems with alarm systems (fire, smoke, and security) and intercoms.
Roofing, siding, and windows.
Disclose any known problems or leaks. Specify age of roof, siding, and windows, if known.
Well and septic systems.
Disclose any known problems with these systems. Provide all service records. Make sure that purchaser acknowledges any special factors (e.g. pump septic system).
Disclose any known problems. Specify age of each item and provide service records, if available.
Disclose any and all known violations of current building code standards. Consider all house systems and structural components.
Sub-standard system performance.
Disclose any household systems that perform in an inadequate manner. Examples - poor availability of hot water or water pressure, air conditioning inadequate to properly cool the house, etc.
Report any and all known environmental issues, including, but not limited to, underground tanks, abandoned septic systems, lead paint, tainted water table, asbestos insulation (usually around pipes), and radon.
What if the boiler fails a month after the closing? Even if you knew nothing about the problem chances are the buyer will think you did - and even the most diligent seller is going to have a hard time countering this accusation. A pre-sale home inspection can help. Problems discovered by the inspector can be repaired or disclosed - and it is very believable that the seller was unaware of any problems that a qualified inspector was unable to find.