[RhysU]

That's why one records the check amount in a ledger kept electronically or physically with the checkbook. You will then always know what you have even if the pesky landlord waits 3 months to cash a check. It's old school but works flawlessly for one person.

(Dunno if banking apps have the ability to record written checks then automatically reconcile when those checks clear. It'd be a nice banking app feature but would reduce revenue obtained from overdraft fees, on which banks gorge.)

For a couple, one needs the has-the-checkbook? mutex to write new checks. Each spouse having a credit card paid down monthly reduces the mutex contention for negative cost (considering float and rewards, ignoring credit-only prices).

Supposing the above fails from time-to-time, there's a defense in depth approach: If you write those checks from a margin-enabled brokerage account, anytime you make a mistake you self-fund the overdraft. This can be useful if the checks you write in a month are small relative to your margin collateral. This can also be useful if one occasionally needs to write a check for larger, one-off purchases where it'll take a few days to move the money around to satisfy the check. This is conceptually nice because a negative checkbook balance stops being haltingly terrifying if you know a regular paycheck will land before some checks clear. Do not trigger margin calls on yourself!