FICA taxes apply to the full amount of the
disability payment for the first six calendar months after the employee has ceased performing services
for the employer. Disability payments will be exempt from FICA starting in the seventh
calendar month after the employee has stopped performing services for the employer.
The LTD insurer should have deducted those from your benefits.
https://www.irs.gov/pub/irs-wd/11-0065.pdf
