Can I claim the expenses of online self-study (subscription fee), online training, exams for certificates? If so, how?
I have been taking online courses via Coursera (US) since 2019 and never claimed any of the expenses. I have also taken some trainings (taught by some professional in US) and wrote exams for certificates which are very expensive in 2020 and 2021.
Can I claim the above expenses in T2022 as a par time study next year?
You can only deduct education expenses for the year they were incurred. But in any event you can’t deduct education expenses which qualify you for a new job or taken for personal enrichment or as an employee. If you are self employed you can deduct the cost for courses to improve your current job performance or are required for your current self employment. Deduct those costs as continuing business education on your Sch C.
See https://www.irs.gov/taxtopics/tc513
Note, in particular, that if you are not self-employed (i.e., you are an employee), you cannot currently deduct the cost of work-related education expenses due to tax reform (the TCJA).
Further note the other requirements:
(1) The education must maintain or improve skills needed in your present work, or
(2) A law requires the education in order to keep your present salary, status or job
(3) The education must not be part of a program that qualifies you for a new trade or business.