Unwary partnerships could face steep fines this year as a result of a new addition to the partnership tax filing form.

The new instructions for Form 1065 include an under-the-radar requirement to disclose a negative capital balance, which is essentially the money partners would receive if the partnership was liquidated, if it’s not already on the partner’s K-1 form. The requirement could draw closer Internal Revenue Service scrutiny of a tax-planning scheme some partners may not be aware is still on the books.

If partnerships miss the requirement—which is on page 30 of a 55-page document, they could face penalties of $195 per partner, per month for up to a year. That would add up quickly for large firms with hundreds of partners.

Even if filing partners follow the reporting requirement, they could be more likely to get examined. That’s because the disclosure could give the IRS a hint as to whether they are potentially using an abusive tax-planning scheme that is restricted by a rule President Donald Trump’s administration left in place during its deregulation effort.

The IRS may take a negative capital balance as a sign that the partner has taken partnership deductions by superficially increasing their property investments in or contributions to the entity and can use it as a tool to more easily find out who’s doing that, tax professionals said.

The new disclosure mandate arrived during what may be “the worst tax season ever” for accountants and tax lawyers, said Michael Greenwald, a partner at Friedman LLP in New York.

“I suspect this one’s going to get lost in the wash,” Greenwald said, in light of all the changes and additions to the Schedule K-1 filing form—where partnerships report each partner’s shares of the tax liability—for the first full year of the 2017 tax overhaul’s changes.

Real estate and startup partners are most likely to need to make the disclosure, according to Greenwald and Kate Kraus, a partner at Allen Leck Gamble Mallory & Natsis LLP in Los Angeles.

“I’m sure people are going to overlook this,” Kraus said. Still, it is unclear whether the failure to report the negative capital account balance might result in a tax under the new partnership audit rules.

Slash One, Save Another

The Treasury Department in June proposed throwing out one part of a set of rules governing the treatment of partnership liabilities, but keeping another. The move was part of Trump’s executive order requiring Treasury to target tax regulations deemed overly complex or burdensome.

Treasury proposed removing temporary regulations issued in 2016 that would have restricted partners’ ability to build up their investment in a partnership by contributing debt, without triggering a “disguised sale” to the partnership, which is a taxable transaction. By increasing that investment or contribution, partners may be able to shrink their tax bills by taking more deductions passed through the entity.

However, Treasury held on to a rule keeping partners from increasing their property investments or contributions, also known as “basis,” so that they can take more deductions with the use of a “bottom-dollar guarantee.” Partners would essentially guarantee partnership debt that they would generally never have to pay, artificially increasing their basis and reaping the tax benefits without taking on any economic risk or hit to their bottom lines.

“Treasury and the IRS continue to believe, consistent with the views of a number of commentators, that the temporary regulations on bottom-dollar guarantees are needed to prevent abuses and do not meaningfully increase regulatory burdens for the taxpayers affected,” Treasury officials said in an October 2016 report to the president on the department’s progress in eliminating old rules.

Regardless of whether they’re aware of the “sleeper” disclosure requirement, not a lot of partners know that the bottom-dollar guarantee technique still isn’t allowed, said Glenn Dance, tax services managing director at Grant Thornton. Dance was special counsel to the IRS associate chief counsel for partnerships until late 2017.

Soon, the IRS will get an indication of who is probably still using them.

“This new disclosure requirement will give the IRS a tool to sniff out any bad guys who failed to get the memo,” Dance said. “Some people seem to view the two sets of rules as inextricably linked, and are even confused about which one got withdrawn.”