JUNEAU (AP) — U.S. Rep. Don Young is updating his financial disclosures to show ownership in a family farm dating to the 1990s and income from oil and gas leases, omissions that a Young spokesman called inadvertent but that Young’s Democratic rival in this year’s election characterized as a betrayal of trust.

Young spokesman Matt Shuckerow said Monday that the failure to include the farm prior to his 2015 congressional financial disclosure was an oversight that became apparent after the 2014 death of Young’s brother, Russell, and the subsequent sale of the property last year. In his 2015 disclosure, Young reported receiving between $250,001 and $500,000 as a result of the sale. Disclosure reports offer ranges to report such things as assets and liabilities.

Young became a partial owner of the farm after his mother died in 1990 but Russell Young operated the farm, Shuckerow said. The Republican congressman derived no income from farm operations but received some income from oil and gas leases, he said.

“For all intents and purposes this was his brother’s farm,” Shuckerow said. “But from time to time, as a legal stakeholder in the property, he was required to sign documentation and agreements involving use of the property and this included different business ventures made by Russell.” Those included private property oil and gas leases, Shuckerow said, adding that it was Young’s understanding that exploration never occurred.

Income from leases in the 1990s was included in Young’s congressional financial disclosures but $4,100 in rental income over three years from a 2001 lease sale wasn’t, Shuckerow said. He said the omission was inadvertent and Young’s filings would be updated to reflect those.

The money was reported on Young’s tax filings, Shuckerow said.

The story was first reported by the Alaska Dispatch News.

Young sent a letter to the House clerk in May asking that his filings from 1995 to 2014 be updated to reflect his one-third interest in the farm during that time. But Shuckerow said that letter would need to be revised. The letter references Young inheriting his stake in 1995 but Shuckerow said that was a clerical error.

The inheritance followed his mother’s death and Young was trying to nail down the correct date, which was not entirely clear due to the probate process, he said.

Shuckerow said Young acted as soon as he realized there was an issue.

“The congressman has been very clear on making sure that Alaskans know that our things are in order. There are oversights from time to time,” he said.

In 2014, the House Ethics Committee found that Young had violated House rules by using campaign funds for personal trips and accepting improper gifts. It issued a letter of rebuke and called on Young to repay the value of the trips and gifts, totaling about $59,000, and to amend his financial disclosure statements to include gifts he had not reported. Young apologized for “a number of instances where I failed to exercise due care in complying with the House’s Code of Conduct.”

Young is the longest serving Republican in the U.S. House. He currently is seeking a 23rd term.

Steve Lindbeck, the Democrat challenging Young, said that by keeping “lucrative land ownership and financial deals with oil and gas companies a secret from congressional ethics officials” Young had “deeply betrayed our trust by putting himself ahead of the Alaskans he should represent.”