Mother Earth News did a test on various storage methods. I wish I had the link. To sum it up, there were still some eatable eggs almost a year later. Now would I eat those eggs if I had a fresher egg, I think not. Eggs in the refrigerator two months are still good, I think I had a few of those over the years. When a egg sits any where fridge, counter top, it loses moisture all the time and oxygen seeps in lowering the quit of the egg. The longer an egg sits the more chance a germ has to find a chink in the eggs amour and gets in. Commercial egg producers with modern equipment, have their eggs sorted and graded as fast as the hens can lay them. Its the distribution time that's the bug, as raymondjames pointed out. When sales are good and the producers have matched production to demand, the time can be as little as a few days. When demand is bad, well any number of BYCers can testify the eggs can pile up in storage.
To the OP question on how long after expiration date are they good for me I'd go no more than a month.