UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of

the Securities Exchange Act of 1934

Date of report (Date of earliest event reported): March 15, 2013

Affirmative Insurance Holdings, Inc.

(Exact name of Registrant as Specified in its Charter)

Registrant’s telephone, including area code: (972) 728-6300

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 2.03. Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

On March 15, 2013, the Company, through one of its indirect, wholly-owned subsidiaries, entered into a $4.8 million loan secured by commercial real estate to provide liquidity to one of the Company’s insurance company subsidiaries, Affirmative Insurance Company (“AIC”). The loan is evidenced by a promissory note secured by a mortgage, security agreement and assignment of leases and rents on real estate located in Baton Rouge, Louisiana (the “Property”). The Property is owned by the Company for investment purposes and includes a building of approximately 177,469 square feet, which is under a lease agreement with a federal agency.

The promissory note bears interest at a per annum fixed rate of 4.95%. The promissory note requires monthly payments of principal and interest with the final payment due on the maturity date of December 15, 2015. As security for payments, the Company has assigned rents due under the federal agency lease to a trustee. Pursuant to an escrow and servicing agreement, the trustee will receive rent due under the lease, make required payments due under the promissory note and maintain certain escrow accounts to pay for the necessary expenses of the Property until the promissory note is paid in full.

The description of the mortgage loan in this Current Report is a summary and is qualified in its entirety by reference to the complete terms of the loan agreements.

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements typically are identified by use of terms such as “may,” “will,” “should,” “plan,” “expect,” “anticipate,” “estimate” and similar words, although some forward-looking statements are expressed differently. Forward-looking statements represent our management’s judgment regarding future events. Although the Registrant believes that the expectations reflected in such forward-looking statements are reasonable, the Registrant can give no assurance that such expectations will prove to be correct. All statements other than statements of historical fact included in this Current Report on Form 8-K are forward-looking statements. The Registrant cannot guarantee the accuracy of the forward-looking statements, and the Registrant’s actual results could differ materially from those contained in any forward-looking statements due to a number of factors, including the statements under the heading “Risk Factors” contained in the Registrant’s filings with the Securities and Exchange Commission. Accordingly, such forward-looking statements are subject to a number of risks and uncertainties and may cause actual results to differ materially from the Registrant’s expressed expectations.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this Report to be signed on its behalf by the undersigned hereunto duly authorized.