I regularly receive 40 free listings a month and am very grateful for them. 

Usually, I spread my use of them out over the month but at both the end of Feb and March, my remaining free listings, which are supposed to be available until 11.59pm on the last day of the month disappeared much earlier than that on both the 29th Feb and 31st March. The loss of free listings I might have otherwise used, was unfortunate, but I just shrugged (at the end of Feb) knowing I would have 40 new free listings the following day.

However, on the 31st March, I had checked to make sure I had a couple of free listings left earlier in the day and then a little later, proceeded to list a couple of items. They were listed at 8.40pm and 10.20pm on that night. I then discovered that I had been charged $1.50 for each - the standard insertion fee, without extras.

I tossed up just living with it or contacting ebay about it but decided that my sales and profit margin are soooo meagre these days that I would follow it up.

Surprisingly, I got a very quick response from ebay. They would credit me with both insertion fees and the explanation is that basically ebay pick a time for expiry of the free listings out of their proverbial hats !!

Here is the information I was given by the CS agent:

"I am aware that you saw 2 free listings on your account prior to listing your items for sale, we are not given an exact time on when the free listing will expire. Th only details that was specified is it will expire at the end of the month and the maximum time frame is at 11:59 pm, so any time of the day the free listing will expire."

That's all very well and we can adjust our listing practice to this ONCE WE KNOW - however apparently ebay don't feel the need to let their seller clientele in general know about this. . . .unless of course you end up having an experience like I did and choose to enquire about it !!