Can you share your depreciation method setting? 

In general, net value (acquisition minus accumulated depreciation) is a base value for depreciation method Remaining Value/Remaining life or Rmeaining Value/Remaining months, while fixed factor depreciation is based on acquisition value.  

I am using Fixed factor depreciation.

i am using life of object in book and already used more than 50% life of object, so i am passing dep value manually during migration of object.

This is method below.

Hello,

You are using declining balance method. Yes, system should use then net value as depreciation basis changing base value every new year (as per Change Base Value parameter setting). 
You have migrated (imported) your objects with accumulated depreciation already, but what was imported depreciation period? Entire depreciation in the last period, somewhere in the middle of current year?

I suspect you have two options:

1) amend Change Base Value parameter to Depreciation Period (system will use net value each month)

2) rollback import and do it again with depreciation split into two figures: accumulated depreciation at the end of last year (depreciation period like 2021-12) and depreciation of the current year (depreciation period 2022-04, it last depreciation was in April and accounting year is equal to calendar). Base value for current year in such case will be then acquisition minus accumulated depreciation end of the previous year.

I am not sure what is your goal, changing base each year means that depreciation calculated for each month in the year is same, while doing it every period means depreciation is constantly decreasing each month.