NEW YORK — Many small businesses still don't know whether they'll win or lose under the new tax law.

Some corporations already know their tax rates are falling, and all businesses can get bigger deductions for equipment purchases.

But owners and tax advisers are waiting for the IRS to write regulations and guidelines explaining and enforcing the law. An accountants' group has asked the IRS to hurry regulations on the biggest changes, including a deduction for many sole proprietors and partners.

Another big question: Can owners deduct the cost of taking clients or customers out to lunch or dinner?