Short-term disability insurance can cover inpatient rehab for drug or alcohol addiction, but it isn't automatic. Most private and employer-sponsored short-term disability (STD) plans will pay benefits for substance use treatment only if a licensed physician certifies that you are medically unable to work because of the condition, and only if the plan doesn't explicitly exclude substance use disorders.
The key is how your plan is written. Many group STD policies, especially those bought by employers from large insurers, treat substance use disorder the same as any other diagnosed medical condition under mental health parity rules, meaning inpatient detox or residential rehab can qualify the same way a hospital stay for a physical illness would. Other policies, particularly some older or smaller group plans and most individual disability policies, contain specific exclusions or limitations for "self-inflicted" conditions or substance abuse, which can reduce the benefit period or deny the claim outright. You have to read your Summary Plan Description or policy certificate to know which category you're in.
Even when substance use disorder is covered, insurers almost always require documentation that the treatment is medically necessary. This typically means a physician or addiction specialist needs to certify that you have a condition severe enough to prevent you from performing your job duties, and that inpatient (rather than outpatient) care is required. Simply choosing to go to a residential rehab program voluntarily, without this certification, usually isn't enough to trigger benefits.
Timing matters too. STD plans often have an elimination period, a waiting period of several days to about a week, before benefits start, so the very first days of a rehab stay may not be paid. Benefit duration is also capped, commonly somewhere between a few weeks and a few months, so a long-term residential program may outlast your STD coverage, at which point you'd need to look at long-term disability, FMLA job protection, or personal leave to bridge the gap.
It's also worth checking whether your plan has a lifetime or per-occurrence limit specifically for mental health and substance use claims, since some older policies cap these differently than they cap physical illness claims, even though many states and federal parity law now restrict this practice for fully insured group plans.
The most reliable way to find out your specific coverage is to call the number on your insurance card or ask your employer's HR or benefits department for the plan document, then have your treatment provider or an admissions coordinator at the rehab facility help you gather the paperwork insurers require, such as a physician's statement and a treatment plan. Many rehab facilities have staff who handle insurance verification and benefits coordination daily and can tell you quickly whether your STD plan is likely to pay.