Checking accounts shouldn't really be used for sums of money like $20k; they're intended for payments-out, so should be restricted to the buffer needed for one

Checking accounts shouldn't really be used for sums of money like $20k; they're intended for payments-out, so should be restricted to the buffer needed for one or two months' payments. They are equivalent to DMZ servers; hold only what is necessary for the service and be prepared to drop them quickly if problems occur. The real money ( such as received salary and savings ) should be in firewalled deposit-only accounts ( like servers in the secure internal network ). Push from the salary receiving account to checking when necessary. Don't accept any requests from the DMZ.