Back Taxes Calculator
Calculate how much you owe in back taxes including penalties and interest.
See the total cost of unpaid taxes over time.
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Back Taxes Estimate
Back taxes are taxes owed from previous years that were not fully paid.
Penalties accumulate as follows:
- Failure-to-file: 5% per month, max 25% of unpaid tax
- Failure-to-pay: 0.5% per month, max 25% of unpaid tax
- Combined max: 47.5% of unpaid tax in penalties alone
Interest:
- IRS charges ~8% annual interest (varies quarterly)
- Interest compounds daily on unpaid tax AND penalties
- Interest has no cap — it grows indefinitely
Example: $10,000 in back taxes from 3 years ago (unfiled) could cost:
- Failure-to-file penalty: $2,500 (maxed at 25%)
- Failure-to-pay penalty: $1,800 (0.5% x 36 months)
- Interest: ~$2,500
- Total: ~$16,800
IRS payment options: Installment agreements, Offer in Compromise, Currently Not Collectible status.
Contact the IRS or a tax professional to discuss payment options.