Reasonable cause means you used ordinary business care and prudence and still could not meet the deadline because of something outside your control. It is a facts-and-circumstances standard, which means the letter matters. A good one lays out what happened, when, why it prevented compliance, and what you did as soon as you could.
What the IRS generally accepts
- Death or serious illness of the taxpayer or an immediate family member, around the due date.
- Fire, casualty, natural disaster, or other disturbance that destroyed records or prevented action.
- Inability to obtain records for reasons outside your control.
- Erroneous written advice from the IRS that you relied on.
- In some cases, reliance on a tax professional, though the courts have narrowed this for filing deadlines.
What it does not accept
- Not having the money. That is what payment plans are for.
- Not knowing the deadline or the rule.
- A preparer who was busy.
- Being out of the country on vacation.
How to write the statement
The IRS reads for four things: the event, its dates, how it prevented you from filing or paying, and how quickly you complied once it was over. Attach proof: a death certificate, hospital records, a police report, an insurance claim. The reasonable cause statement puts those in the order the reviewer expects.
Where to send it
In response to the penalty notice, at the address on the notice, or on Form 843 if the penalty has already been paid. If first-time abatement also applies, ask for it first; the IRS will use it before considering reasonable cause and you may not need the story at all.
Common mistake
Writing an apology instead of a timeline. The reviewer is not scoring remorse. They are checking whether the facts meet the standard.