Dear candidate

SSC conducts CGL examination only in 3 tier for the various posts under ministries.many ministries required typing test ( which you can call tier 4 but it's actually specific to some ministries only) typing test is of only qualifying in nature so don't panic about it you can qualify it by 2 months practice only.

Many ministries don't require any typing test so you don't have to worry about it.

Hope this will helpful.