In your particular example as the transaction date is considered your payment date, it makes sense that they are collecting funds from you at the last possible day, ensuring that you are enjoying full credit period.
Q)Why is it always last day?
- As pointed out not all accounts do this, some do it.
Q)Why do some site do this? What is the credit card company's reason for setting the default payment date as the due date
- If its a card site offering this, then they do not want to get sued by customer for recovering money before their payment due date ... you have all kinds of people out there, so better be safe and put the date as the last day of due date.
- If its some other site, then its a Bad UI practise, but easy to code functionality. Pick up the date which is readily available, rather than X (1-3) days before computation. Plus they cannot hardcode the value of X, it has to come from some where. Then it becomes more fanciful solution, a radio button to choose from pay immediate or pay by date etc ...
Q)I tend to set the payment date to a day far sooner than the statement's due date. Is it rational?
- Yes it is rational and you should make the payment couple of days in advance as there could be chances says once in 25 times you make a payment that there is a bank or other technical error and you have time to rectify it. Else you would be charged a late fee plus interest.
- I know some one may say if it happens you can always call up the card company and request them to reverse these as it was one off case and not due to you.
- If you look at it other way, if you pay couple of days early, you dont loose anything at all. Assume you pay from your checking account, if you are paying from saving, a 2 days interest is not that big a deal.
Q)Is it actually in my best interest to not muck with the default date, thereby collecting more interest?
- As above it is actually in your interest to muck with the default date, unless your bank account and the card provider are same.