Taxes in the US are unnecessarily stressful. I remember going to H&R Block and being sent home to find some piece of supporting documentation because it was “really important”. I turned the whole apartment upside down but wasn’t able to find it. Went back to the tax preparer in a state of high anxiety. When I asked what would happen if I couldn’t find the document and was told the impact on the final assessment could…
That's the financial impact. Depending on what you're missing, the nonfinancial might be opening yourself to perjury, because you're knowingly claiming a falsehood as a fact on a tax return (even if it's financially in the government's benefit)... never mind potentially screwing up future tax returns in the process.