Currently, in the Army, individuals typically sign up for a minimum of four years, but can extend their contract or leave after that period with proper notice.
“The Bill for limiting the time of service in the Army, and for amending the Acts for rendering effective the services of the Chelsea and Greenwich Out-pensioners, provides that no person shall be enlisted as a soldier for a longer term than ten years in the infantry, or twelve in the cavalry, artillery, or other ordnance corps, to be reckoned from the day on which the recruit shall have been attested, if he shall have stated himself to be then of the age of eighteen years, or if not, then from the day on which he will complete the age of eighteen years. That any soldier, after completing his term of service, may be re-engaged for any term not exceeding eleven years in the infantry and twelve years in the cavalry and artillery. Provided that both the first and second terms of service may be prolonged for such further, not exceeding on year in time of peace or two in time of war, as shall be directed by the commanding officer on any foreign station; and that any soldier who shall give notice to his commanding officer, after completing his second term of limited service, that he is desirous of continuing in her Majesty’s service, may be continued as a soldier until three calendar months after he shall have given notice of his wish to be discharged.”
The Stamford Mercury, 19th March, 1847.