In respect to the lender, a borrower will be required to get a new appraisal if it has taken more than three months to get his new home mortgage refinanced. This is due to the volatility in the real estate market. Home prices and sales can change dramatically in a short time, therefore, the appraisal itself is only considered valid, in the lender's opinion, for a full three months.

On the Other: It is Valid for at Least a Year.

However, a borrower can use an appraisal for a number of different situations. To fight his tax-assessed value, for instance, the appraisal amount can be valid for up to a full year from the date of the appraisal. Also, when deciding on a sales price for his home, the appraisal amount should be considered relevant for at least a year if home prices in the borrower's area are considered stable.

Bottom Line

An appraisal's date matters given the situation in which it is used. If it is being used for any purpose other than for a mortgage, the borrower can use his discretion as to the validity of the numbers listed on the appraisal. An appraisal is a slightly subjective document, and a second appraisal ordered could come back with an entirely different price, although preferably close to the value of the first.

Source:

EFannieMae.com: HVCC FAQs

FederalReserve.gov: A Consumer's Guide to Mortgage Refinancing