Is there a penalty for not sending in the ES payment in time? i.e. for 2nd qtr 2007, the deadline is June 15th, which I totally missed :)

Considering that this is just an estimated, as long as I include enough $ in the payment, it should be OK?

A late payment penalty will be calculated when your return is completed next year, unless you are due a refund.

Even though you missed the June 15 deadline, you should still send the payment in as soon as possible. If you owe a penalty, it will be calculated when you file your taxes next year, and the amount of the penalty will depend on how many days late your payments were. So get your estimated payment in ASAP. Depending in the magnitude of the late payment, you might want to overpay this quarter's amount by a few $$.

Agree. Make the estimated payment ASAP!