Shares of tax preparers Jackson Hewitt Tax Service ( JTX) and H&R Block ( HRB) plunged Thursday after regulators said they are considering restricting profitable refund anticipation loans. The Internal Revenue Service, along with the Treasury Department, is soliciting public comments on a proposal that would restrict the marketing of refund anticipation loans (RALs) and similar products, such as refund anticipation checks and audit insurance. The proposal comes in conjunction with the IRS's final regulations issued Thursday regarding updated disclosure and privacy laws for taxpayers on personal information held by tax preparers. Shares of Jackson Hewitt, based in Parsippany, N.J., nosedived 23.1% to a new 52-week low of $24.13, while H&R Block of Kansas City, Mo., fell 4.6% to $17.75, after touching a 52-week low intraday on Thursday. The regulators are considering a proposal that tax return preparers be prohibited from disclosing taxpayer return information to lenders for the purpose of selling RALs -- short-term cash advances given to customers based on projected tax refunds -- and similar products over concerns that it "may provide preparers with a financial incentive to take improper tax return positions in order to inappropriately inflate refund claims," according to a notice. "In general, RAL amounts are capped by the amount of the refund claimed on a tax return," the notice said. "Therefore a preparer who inappropriately inflates the amount of a refund is able, directly or indirectly through arrangement with RAL provider, to collect a higher fee."