If the account lists only his name as the owner and you do not have any signatory authority - and even if you did it really would not matter as the account would appear to be his alone - then no, you can not withdraw the funds from the account.  I strongly advise you not to deposit anything else in the account until you are added as a joint account holder with the bank.  That means adding you within the bank system and filling out a signature card. Otherwise the funds will be considered to e only his and if he passes away you may have to go through probate to have the finds released.  Double check with an attorney in your area on the issue of account frozen at the time of death. Some accounts under a certain amount of money my not be frozen.  Good luck.