Taiwan is tightening its military service exemption rules in a sweeping overhaul expected to halve the exemption rate and add thousands of conscripts to the armed forces each year as the island grapples with persistent manpower shortages.

Under the revised standards, which took effect last week, men will generally be exempt on weight grounds only if their body mass index (BMI) exceeds 45, while the height threshold for exemption has been lowered to 144cm.

Rules covering hypertension and other medical conditions have also been revised, while alternative service will be divided into two categories according to physical condition.

According to the island’s interior ministry, the changes are expected to cut the exemption rate among conscription-age men from about 16 per cent to 8 per cent.

“Based on about 90,000 conscription medical examinations annually, the changes could add about 4,500 men to regular military service and 2,700 to alternative service each year,” a ministry official said on Monday.

The overhaul comes as Taiwan’s armed forces face personnel shortages while bringing growing numbers of new weapons systems into service.

The island’s defence ministry figures show the volunteer staffing rate stood at 76.62 per cent in June, below the military’s 80 per cent target for a third consecutive year.

Under the previous standards, men with a BMI below 15 or above 35 could be exempted. The new rules eliminate the lower BMI threshold and raise the upper barrier to 45. For a man measuring 170cm, the weight threshold for exemption rises from more than 101.3kg to more than 130.2kg.

Height requirements have also been tightened. Previously, men 154cm or shorter or 196cm or taller could be exempt. Under the new system, only those measuring 144cm or less can be exempted on height grounds, while those at least 150cm tall qualify for regular military service.

Alternative service will be divided into Category A and Category B. Category A personnel can be assigned to field duties with agencies such as the police and fire services, while Category B personnel will generally perform office-based, government support or social service duties.

The revisions also make it harder to secure an exemption on hypertension grounds, an issue that has attracted particular scrutiny following a draft-dodging scandal involving Taiwanese celebrities.

A diagnosis of hypertension, or high blood pressure, alone will no longer be sufficient. Applicants must have at least moderate hypertension accompanied by organ damage, and undergo hospital observation and continuous 24-hour blood pressure monitoring.

The scandal, which erupted early last year, exposed an alleged draft-evasion network involving dozens of people, including prominent singers and musicians.

In the first major court ruling stemming from the case, the New Taipei District Court on October 20 sentenced 14 defendants – nine entertainers and five other individuals – to suspended prison terms, with probation conditions that include payments to the public treasury and community service. Dozens of other prominent figures implicated in subsequent rounds of the investigation still face legal proceedings.

The interior ministry said the new standards were not the strictest Taiwan had imposed, drawing partly on rules in force from 2003 to 2007, when the exemption rate was about 8 per cent.

It compared Taiwan’s current rate of about 16 per cent with about 5 per cent in South Korea and 3 per cent in Singapore, which also have conscription systems.

Other medical criteria have been adjusted in both directions. The rules for medical discharge following a cancer diagnosis have been relaxed, while previously treated pulmonary tuberculosis must now be accompanied by at least mild impairment of lung function to qualify for exemption.

Shen Ming-shih, a senior analyst at the government-funded Institute for National Defence and Security Research, said the overhaul should be viewed as part of a broader assessment of Taiwan’s defence requirements rather than a response to individual controversies.

“The adjustments should not be about responding to whatever particular problem happens to emerge at a given time. They should be based on an overall assessment,” he said.

“The primary objective, of course, should be to strengthen overall combat readiness and training, as well as the armed forces’ defence capabilities.”Taiwan’s physical classification standards for military service have been revised 19 times since 1974, reflecting changes in the security environment, concerns over fairness in conscription and the armed forces’ evolving manpower and force-planning requirements.

Taiwan’s declining birth rate is shrinking its pool of military-age men. The number of eligible conscripts fell below 100,000 in 2023 and is projected to drop below 80,000 by next year, increasing pressure on the military to make better use of its available manpower.