IRS send me a letter saying I owe a certain amount of money even though I already paid my accountant?

If you recently gave the money to the accountant I would assume the IRS mail was sent out before your payment posted. If you trust an accountant enough to have them do your taxes you should communicate with them and ask them to check for an update on the payment posting. I am sure they would be happy to provide you proof of the IRS records. Also check with your bank to see if the payment has cleared. If so get a copy of front and back of the check and give to your accountant so he can provide this information to the IRS so they can trace your payment.

Your tax payment goes to the IRS, not your accountant. If he/she is the one filing your return you should have given them a check for the right amount made out to the Internal Revenue Service and another check for the cost of the accountant.

You paid the accountant a fee to do your taxes. That's his money, not the IRS's. If you had owed the IRS, you would have written a separate check.

Look at your tax return, what does it say the amount owed was?

The money you paid the accountant is tax deductible as a tax preparation fee if you itemized.

Take your letter to your accountant for an explanation,it is up to them to correct the problem,but if they don't,your still on the hook for the money.

I mailed the total payment but still received a notice from the IRS? I've tried several times to contact them by phone and the IRS website wasn't helpful. What do I do now?