Guides
For when the paperwork has already gone wrong
Nobody searches for an expense tracker at eleven at night. They search for what happens when the letter arrives, or when April is next week and the box is still full. These are written for those moments.
Every figure in here is linked to the IRS document it came from, and nothing in here is tax advice. We are software people, not accountants, and the guides say so where it matters.
Audited with no receipts: what actually happens and what to do next
What an IRS correspondence audit actually asks for, how to rebuild an expense when the receipt is gone, and why an estimate is a poor substitute for paper.
Lost your receipts: how to rebuild a year of deductions before you file
How to reconstruct a year of business expenses from card statements, order histories, email and your camera roll when the paper is gone.
Missed a quarterly tax deadline: the penalty math and how to stop the bleeding
The underpayment charge is daily interest on the shortfall, not a flat fine. Here is the arithmetic, the four 2026 dates and the safe harbor that ends it.
Work out the number first
Before you read anything else, it usually helps to know what you actually owe. The calculator does the 2026 arithmetic in your browser, with no signup and no email.