The maximum age for Army recruits has been raised from 26 to 33, the Ministry of Defence (MoD) has confirmed.
Troops could serve in uniform until they are 55
The MoD denied there was a recruitment crisis, saying it was merely bringing the army into line with the maximum recruiting ages for other armed forces.
The change will mean servicemen and women could remain in uniform up until the age of 55.
There were more than 12,700 new Army recruits last year - but almost 14,500 personnel left the service.
More career options
The age limit also applies to the RAF and Navy.
"This brings the Army into line with the rest of the services, including the ultra-fit Royal Marines who have recruited 33-year-olds for some time," the spokeswoman said.
The MoD denies the Army is losing recruits 'hand over fist'
The spokeswoman said the normal 22-year period of service was likely to remain, which would mean recruits would be able to stay in service until the age of 55.
The minimum age for recruits is unchanged at 16-and-a-half, but troops are not able to take part in operations until they turn 18.
Army band musicians are exempt from the new rules - the maximum age for them is 36 years and 11 months.
An MoD spokeswoman said there had been a 16% increase in recruitment to the services in the past year.
Btu she said a buoyant economy meant young people had a number of career options open to them.
"Of course, like any large organisation, the recruiting environment is proving challenging at the moment and that is why we have been investing in our successful advertising campaigns."
News of the rise in recruitment came as the Conservatives warned of a "retention crisis" in the armed services.
The MoD spokeswoman said it was a "myth" the recruitment age was being raised because the Army was losing people "hand over fist".
She said the number of people leaving the service was a normal turnover.
The ministry added that the recruitment of 12,700 personnel was "deliberate" and in line with announced policy.
"We are drawing down the size of the army by design over the next two or three years," a spokesperson said.