The CP51B is the second notice in the CP51 series for individual income tax balances. You received the CP51A and didn't act. The IRS is reminding you again, with increased urgency. The balance has grown because penalties and interest accrued since the first notice.
Where You Stand
You're two notices into a collection sequence that leads to levy action. The CP51C comes next, followed by the final levy notice. Each step narrows your options and increases your cost. Resolution at the CP51B stage is still relatively simple: pay in full, set up an installment agreement online, or call the IRS to discuss options.
The Growing Balance
Compare the CP51B balance to the CP51A balance. The difference is entirely penalties and interest. The failure-to-pay penalty adds 0.5% per month. Interest compounds daily at the federal short-term rate plus 3%. On a $15,000 balance, that's roughly $100 per month in penalties and $60 per month in interest. Every month you wait costs $160.
Act Now
Every resolution option available at the CP51A stage is still available now, but the window is closing. After the CP51C and the final levy notice, you're in formal collection proceedings that may require CDP hearing requests, detailed financial disclosures, and professional representation.
If you've received a CP51B, call us at (813) 229-7100. Don't wait for the CP51C.