Revisions to the tax treatment of pari-mutuel winnings that will be highly beneficial to horseplayers were approved on Monday by the Internal Revenue Service and U.S. Treasury Department, with the rules to go into effect no later than Nov. 14, according to the National Thoroughbred Racing Association.

The approval Monday of the revisions, which will effectively raise the threshold at which winnings are taxed, is a major victory for horseplayers. Under the revisions, bettors would be allowed for the first time to count all wagers made in a specific pool for the purposes of determining whether federal tax-reporting and withholding requirements are triggered, rather than the base wager.

Tax-reporting is currently triggered when a bet pays off at excess of 300-1, when calculated on the base wager, with automatic withholding kicking in if the payoff is also in excess of $5,000. Under the new rules, those triggers would be calculated based on the total amount bet in the pool, and they would therefore have the most impact in exotic pools. For example, if a player bet 48 different combinations in a trifecta pool at a $1 base, the reporting and withholding requirements would not be triggered unless the payoff was in excess of $14,400.

The NTRA spearheaded the lobbying drive to get the revisions considered by IRS and the Treasury over the last two years. In a statement, Alex Waldrop, the organization’s president, called the revisions “among the most meaningful regulatory advances made by our industry in decades.” The association estimated that handle might grow by $1 billion in the next year as a result of the revisions.

“The results of this much-needed measure will be horseplayers keeping more of their winnings, racetracks generating more pari-mutuel handle, and government collecting additional tax revenue,” Waldrop said. “This is a sure bet where everyone wins.”

The new revisions will not take effect for all bet-takers, which must administer tax-reporting and withholding, until 45 days after the rule is published on Wednesday, the NTRA said. That will give some bet-takers the time it takes to put the new logistical changes in place, though some bet-takers that have already invested in anticipating the change may put the rules in effect on Thursday, the NTRA said.

“For the industry to fully realize the benefits of modernized regulations for pari-mutuel withholding and reporting it is essential we deliver a seamless transition to our customers,” Waldrop said.

In the case of a physical ticket, only the bets on the winning ticket will count as triggering the tax-reporting and withholding requirements, to protect against players picking up losing tickets that they did not bet. However, all bets in the pool for a customer of an account-wagering operation will count, even if the bets are spread over multiple tickets, since there is a clear electronic accounting trail for the bets tied to the customers.

Racing lobbyists had tried for years to get the revisions through the federal legislature, but the changes were often attacked as political handouts to gamblers, and those efforts were never successful. The NTRA changed tack two years ago to directly take the industry’s case to the IRS and Treasury, a strategy that ultimately paid dividends. The NTRA also recruited industry stakeholders and thousands of horseplayers to send letters in support of the revisions.

“This is a major victory for all pari-mutuel wagering customers,” said Judy Wagner, the Horseplayers’ Representative on the NTRA’s board of directors. “It would not have occurred without the leadership of the NTRA and the support of thousands of horseplayers who participated in the process to modernize these regulations.”

(An earlier version of this article incorrectly stated an amount that would trigger authomatic withholding.)