Dude,

I haven't tried it because I have a spreadsheet I have used to check my loan - have never found an error on mine (AMP Bank). However I have spoken to people who have found errors on their loans (mainly with the major banks).

Most common error I have heard of is the "leap year" error which most banks seem to sneak in - they quote an annual interest rate (eg. 8%) but during a leap year they still divide this by 365 instead of 366 so basically you are charged an extra days interest that year. I notice that the conditions on the $100 offer require you to check 4 years of history so this is probably the error they are counting on finding.

Other relatively common "errors" are calculating interest on the daily balance BEFORE any payments are deducted. eg. Outstanding balance today is $100,000 but you make your monthly payment of $1000 - the correct calculation should be to work out interest on 99,000 but some banks have been caught "mistakenly" calculating on 100,000 - this one can add up to quite a lot of interest over the life of the loan. Also incorrect rounding of interest rates and/or interest deducted from account are almost always in banks favour as are mistakes in changing interest rates (eg. rate drop in middle of month but not reflected in interest calculation until the next month)

So would I buy the program? Probably not because I know how to check it myself. If you don't have this knowledge then it comes down to a bit of a gamble - most likely the program will only find a few dollars but there is the real possibility of many thousands of dollars in errors. If you have a big loan then I would probably give it a go (bigger the loan the bigger any error will be) or find someone who can check it with a spreadsheet.

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"Computers can do that????" - Homer Simpson