TDS Accumulation issue

Dear Experts,

TDS (Basic, surcharge, E cess and HS cess) calculated by system and manual calculation differs.

Is it because of accumulation?

I have set Accumulation Type as " Per Calendar Year" and "Acc. W/tax to Max"

Even if I post two different invoices of same amount to same vendor, TDS calculation is different.

If it is bacause of Accumulation, can I set setting to "No Accumulation"?

Since several posting are already made, will there be any implication of changing Accumulation type to " No Accumulation"?

Regards