WASHINGTON — Beginning Tuesday, veterans filing or appealing claims must use standardized forms, a controversial move that the VA says will streamline the process, but some advocates say it will cost tens of thousands of veterans their benefits.

“This change is largely unnecessary and it’s been made solely for the convenience of the VA,” said Gerald Manard, Veterans of Foreign Wars National Veterans Service deputy director.

Until now, veterans have been able to begin the claims or appeals process by submitting a letter or even a scrap of paper. That informal system preserved the initial date of their claim, meaning any benefits awarded would go back to the date that the VA received the note. Under the new system, benefits will still go back to the date of claim or appeal, but the clock starts only when a veteran files standardized VA paperwork.

If the VA receives a handwritten note, department officials will send back a response informing the veteran of the proper paperwork and where to find it, though they will not send the paperwork itself. Replacing the informal claim is an “intent to file” form, for those who want to file a claim but still need to gather more information or documentation.

VA officials have said the new process will reduce confusion and make it easier to file claims.

Thomas Murphy, VA’s director of compensation service, said inaccurate information in informal claims often led to delays in compensation for veterans.

“It was difficult to keep track of and veterans often had wrong dates of claim as a result,” he said.

Veterans advocates, however, are incensed by the mandate, and officials with Disabled American Veterans and VFW say they are mulling legal action to stop the change.

Older veterans, who may not own a computer, could be disproportionately affected, along with those suffering from brain injuries who may have difficulty navigating the formal site and keeping track of user names and passwords, Disabled American Veterans’ National Service Director Jim Marszalek said.

“Those are the people we’re leaving behind, those most in need,” he said.

Another worry is that tens of thousands of veterans could potentially lose months of benefits in the confusion over the new rules and the wait for the VA to respond to them. That’s because the clock won’t start on benefits until the date a veteran submits the proper intent-to-file form — meaning many who mistakenly file informal claims will have to wait for the VA to respond and start over. The VA has no deadline to respond and will not send the claim forms with their letter, another sticking point for advocates.

“That’s unfairly penalizing veterans,” Marszalek said.

Murphy points out that the VA announced the deadline six months ago and even created a new avenue to file informal claims — a call center 800 number. He added that the change in the VA simply brings it in line with other federal agencies, such as Social Security and Medicare, and that it’s unnecessary to send veterans forms when responding to improperly filed claims.

“I believe we’re at such a place in society that we don’t need to be sending you a form,” he said.

Among the many controversies swirling around the VA is a backlog of hundreds of thousands of disability claims that has dogged the department for years. The change could help the VA with the backlog, because veterans who have trouble with the new system or mistakenly file an informal claim will delay or give up on filing their claim, Manard said.

“Thousands of veterans who haven’t got the word or who haven’t understood what they saw in the newspaper or magazine … are going to do what they’ve always done,” Manard said.