we can't see the tax return (not sure which year is involved) or the notice. do not post personal info here - this is a public forum. if you don't understand the notice, you can call the number on the letter for a further explanation. at that time if you believe you the tax authorities are in error, you can ask what documents you can submit to prove you don't owe. I realize this might be difficult because many people throw out documents after a couple of years. It is strange that you would get the first notification maybe five or so years after filing..
if you still don't understand the issue after talking with agent or can't comply with the documents requested, if any, then it would seem your only options are to pay or seek the help of a pro if significant $$$$ are involved. The pro may be able to negotiate a settlement.
