Share your insights or perspective on the financial matter presented in the input.

Are tax deductions voluntary?
There are many people who have deductions far above the standard deduction, but still don't itemize. That's their option even though it comes at a cost. It may be foolish, but it's not illegal.  If @littleadv citation is correct, the 'under penalty of perjury' type issue, what of those filers who file a Schedule A but purposely leave off their donations? I've seen many people discuss charity, and write that they do not want to benefit in any way from their donation, yet, still Schedule A their mortgage and property tax. Their returns are therefore fraudulent.  I am curious to find a situation in which the taxpayer benefits from such a purposeful oversight, or, better still, a cited case where they were charged with doing so. I've offered advice on filings return that wasn't "truthful". When you own a stock and cannot find cost basis, there are times that you might realize the basis is so low that just entering zero will cost you less than $100 in extra tax. You are not truthful, of course, but this kind of false statement isn't going to lead to any issue. If it gets noticed within an audit, no agent is going to give it more than a moment of time and perhaps suggest, "you didn't even know the year it was bought?" but there would be no consequence.  My answer is for personal returns, I'm sure for business, accuracy to the dollar is actually important.