Sorry to interrupt your vacation that started when the kids finally went back to school (love that Staples "most wonderful time of the year" commercial), but your tax professor, Uncle Sam, has an assignment for you.

Your third installment payment of 2006 estimated taxes is due tomorrow, Sept. 15. Actually, you just have to get it in the mail so that the envelope's postmark shows that date, the same "timely return" standard (Section 7502 of the Internal Revenue Code) accepted for your annual 1040.

I toyed with mailing our third quarter 1040ES voucher tomorrow. That would give the hubby and me a few more days ownership of our money. However, I opted to once again e-pay the IRS via the agency's Electronic Federal Tax Payment System (EFTPS).

As you might recall from this earlier post, I ran into a few bugs the first time I used the system. This time, though, it went very smoothly ... once I dug out my sign-up paperwork to find my PIN and password. Also, I avoided the primary problem I encountered initially -- a rather unwieldy multiple payment system -- and chose to make only this third quarter payment. I'll just come back next year to make the final 2006 installment due in January.

The official IRS info on EFTPS can be found on this Web page. If you're interested in signing up, you'll find a link there that will take you the proper site. However, it's too late to use the system to e-pay this quarter's estimated tax. While you can enroll online now, you'll have to wait for the IRS to process your data and then send you a confirmation by snail mail before you can actually sign on and pay.

Once you're set up, though, you also can use the system to pay any taxes you might owe in April with your regular 1040. If you e-file, that'll save you the fee, typically around 2.5% of your tax bill, that Official Payments Corp. and LINK2GOV charge to process your credit card tax payment.

But if you're not already an EFTPS participant, get a 39-cent stamp and drop this quarter's payment into a U.S. Post Office box. Then get to your computer and check out EFTPS so you'll be ready to e-pay in the future.