Quick Mistake Proofing Ideas for Preventing Date Entry Error

I found a new failure mode for online bill pay. I had an electric bill due April 24. I mistakenly entered May 23 as the pay date 

So, by April 30, I had a late payment termination notice from the electric company. Kudos to them for the fast cycle time on getting those out. I paid the bill via credit card on their website. 

I’m not sure how to error proof “wrong date.” You?

It is easy to put in a filter that checks and then puts a big flash message:

  “The date you entered is after the due date. Are you sure you don’t want to put in a date prior to that...”

You can also make the data entry bias toward a on-time payment: require an extra step to go beyond the due date, default the value to be the due date... How you implement this would depend on the entry method.

It is really easy to do well if you are using calendar point and click – grey out all the post due date entries, if click on a greyed out entry, pop-up a message that says “that date is after the due date are you sure...” It gets less effective/cool if it is just text entry...

Even with text entry thought you can popup the message on submit of the form if the date is too late (so they enter the wrong date but you catch it before the action is completed).

You can also follow up with (using this method alone is better than nothing but it is pretty lame so I wouldn’t suggest it as the only method unless nothing else can be done reasonably) email saying “you entered a date after the due date in your last bill payment, if you don’t pay before that late fee…

Anyone what to hire me for a few minutes at a time to think of ways to make it harder to make an error just let me know. I don’t like processes that allow errors so have become fairly good and thinking up ways to make it harder pretty quickly :-)

Related: Mistake Proofing Deployment of Software Code - Improving Software Development with Automated Tests - Poka-Yoke Assembly