DH wrote a check to the US Treasury; IRS. I just viewed it on line. It is very clear and legible. It clearly says $XX37.00. Someone wrote on the front of the check, midway, near the signature $XX57.00 Now if he underpaid the IRS, they would send a bill for the deficiency. I don't think that they would change the check amount. It is also so clear and legible that I don't think someone 'guessed'. It is also obvious that the writing is different.What do you suppose happened? Could an unscrupulous check clearer add $20 for themselves, send the IRS the correct amount and not think that anyone would question the IRS? I have no idea. I am just guessing. I will go to the bank when it opens.