Neither of your IRA custodians know about your other account. They will calculate the RMD amount only for the assets in that account. You need to total the value of all your IRAs and divide by the RMD divisor for your specific age and situation. The custodians will not have the information to do that. Also, be careful, most custodians, if you have multiple IRA accounts (maybe you some assets in a type of managed strategy and some not), will calculate the RMDs for each account and not provide you a total RMD.
