I am helping my clients to see their house, and we received a cash offer, the buyer provide his bank statements showing the balance in the account, how can we verify if it is true, do we need authorization from the buyer in order to contact the bank for that?

For me it is usually provided on a bank letterhead and you can call the bank using that information.

My client want to buy a house, however, he does not agree with my CMA value I come up with using data from MLS, instead, he would use HCAD\'s market value for his offering price. And he is always over bid by other buyers. Is that HCAD market value accurate? If not, how should I explain to him?

HCAD is not accurate. The value is set for a year and based on data from the prior year and a Texas county appraisal district may not increase the appraised value of a homestead by more than 10% in a given tax year. \n\nIf you do a CMA based on current information in MLS that is what you should go by. Your client could also request a desktop appraisal from an appraiser.