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IRS notice, decoded

CP501: Balance Due — First Reminder

What it is

A reminder that the IRS still shows an unpaid balance for a tax year. Second letter in the collection series — the tone firms up but no enforcement action is happening yet.

Why you got it

Sent when a prior balance-due notice (usually a CP14) got no payment or response.

The deadline structure

The notice prints a pay-by date, typically about 21 days out. Interest and penalties keep accruing until the balance is paid.

The pay-by date printed on YOUR notice controls.

How to respond

  • Pay online at irs.gov/payments
  • Set up a payment plan at irs.gov/opa
  • Call the number printed on the notice to dispute or discuss

What ignoring it leads to

The IRS sends a CP503 — a second, more urgent reminder. The balance keeps growing, and a federal tax lien becomes possible as the series escalates.

Next letter if nothing changes: CP503

Where you are on the IRS collection ladder

Balance-due letters escalate in a fixed order. Responding at any rung — paying, setting up a plan, or disputing — stops the climb.

  1. 1
    CP14

    First bill

  2. 2
    CP501You are here

    First reminder

  3. 3
    CP503

    Second reminder

  4. 4
    CP504

    Intent to levy (state refund)

  5. 5
    LT11 / LETTER 1058 / CP90

    FINAL notice — hearing rights

If nothing changes, the next letter would be CP503 (second reminder).

First: make sure this notice is really from the IRS

  • The IRS initiates contact by U.S. mail — it does not call, text, or email you first
  • The IRS will NEVER ask for payment by gift card, wire transfer, cryptocurrency, or payment app — anyone who does is a scammer, full stop
  • Any payment by check is made payable to "United States Treasury" — never to a person, a company, or anyone who called you
  • To check a letter's legitimacy independently, call the IRS at 800-829-1040 (the main line, not a number from any email or text) or look the notice code up at irs.gov

Mistakes people make with a CP501

  • Waiting for the IRS to 'figure it out' — the series escalates automatically on a clock, not on a human review
  • Not opening it because the first letter was ignored — each rung removes options

Official sources

Our summary paraphrases these sources. Last verified: BUILD-DATE 2026-06-09 — re-verify before launch; scamCheck added 2026-07-11 (verified 5071c/4883c anti-impersonation language reused). Your printed notice always controls.

NoticeKey is not affiliated with, or endorsed by, the IRS or any state tax agency.

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