Cheques are a pain but online banking can go wrong with a typo. Perhaps this is another reason to use services like TextExpander or 1Password, to have the correct sort code and account numbers to hand. But when you’ve been given a new account to pay into, check it first.
Transfer a single penny.
If the recipient gets that, you’re good to go: you know for certain that it works.
There is the chance that someone else is sending a penny – why does that sound rude? – on the same day but yours will arrive with your reference.
It’s an idea nicked from PayPal which checks out your bank details by doing something similar: it deposits some random, if very small, amount and you have to confirm what that amount is. But that’s done as much to confirm that you are you as it is to check that the bank details have been entered correctly so I’d keep it simple.
This does depend on who you’re paying. If it’s a firm you don’t know, you may find it hard to learn whether they got the payment or not. But then if then phone up demanding to know where your big cash transfer is coming you get to say well, duh, if you’d check your accounts more often you’d be paid now.