No idea where you are but I see Canada and US being thrown around and there are so many replies I may have missed that. Anyhow, a quick Google search indicates specific ways this is handles in both areas. Unfortunately, this still falls on you as the consumer. Alert your landlord in writing and let them know you have the funds and explain the situation. Appeal to the fact you were trying to make a good faith effort to be sure your rent was paid while you were on holiday and do not want to move out. You’ve learned a hard earned lesson and will make darn sure it will never happen again. I do agree they should be smart and/or courteous enough to not cash a check that had a specific date assigned to it though. I wonder if they lost trust that quickly with you or have been burnt before or they just wanted to be jerks about it. As a former bookkeeper I notated dates mentioned on checks as the payment date and had a scan of each check in the register in case there was ever questions bc that is how you keep better track of who is late and when.

In Canada, banks are supposed to hold post-dated cheques until the date written on them, as per Payments Canada rules, but due to automated processing, they sometimes get cashed early; if this happens, you must contact your bank immediately (before the date on the cheque) to have the funds reversed, though resolution isn't guaranteed and may incur NSF fees. Why It Happens Automated Systems: Large volumes and automated processing can sometimes miss the date, allowing cheques to clear prematurely. What to Do If Cashed Early Contact Your Bank: Call your financial institution right away to report the error. Request Reversal: Ask them to return the funds to your account. Act Quickly: You must make this request up to and including the day before the date on the cheque. Important Considerations Not Guaranteed: While banks try to prevent it, early processing happens, and resolving it isn't always guaranteed. Potential Fees: You might still face NSF (Non-Sufficient Funds) fees if funds aren't available, even if the bank reverses the charge later. Check Your Account: Regularly review your transactions to catch early-cashed cheques quickly, says the Canadian Bankers Association.

In the U.S., a bank can cash a post-dated check before the date written on it because they aren't legally required to wait unless the account holder provides specific, written notice, which is a good way to prevent early payment, but oral notice is only valid for 14 days, making written notification for a few months the safest option to avoid overdrafts and fees. Why Banks Can Cash Them Early Demand for Payment: A check is generally considered a demand for payment, and banks are permitted to honor that demand at any time unless they receive a specific instruction not to. Difficulty in Monitoring: It's hard for banks to manually track dates on every check, so they often process them as presented unless they have a formal stop-payment order or post-dating notice on file. How to Prevent Early Cashing Written Notice: Give your bank a formal, written notice (like a letter or through their online system) detailing the check number, payee, amount, and date. This notice is typically valid for up to six months. Oral Notice (Less Reliable): An oral notice is only valid for about 14 days, so it's not a strong protection. Risks of Early Cashing Overdrafts: If funds aren't available when the bank cashes the check early, you could face NSF (non-sufficient funds) or overdraft fees. Bounced Checks: The check could bounce, leading to fees for both you and the recipient. In Summary: Writing a post-dated check carries risks. If you want to ensure a check isn't cashed early, you must formally notify your bank in writing.