Ideally depreciation would be the same every month regardless of days in the month. However if the start date is on the 7th, then it is preferable to have:
* The first and last months calculate based on days,
* The the months in-between be the remaining months,
* So those middle months are the same and only the first month and last month is different.
AssetAccountant™ treats partial months depreciation in exactly the way described above.
So, for an asset purchased and put into use on 15 Jan we would calculate depreciation as 16/31 of the normal monthly depreciation amount have a similar treatment at the tail end.
We have two options for the months in between - 'Days per month' or 'Equal months'. In the Equal months case, each month gets allocated 1/12th of the depreciation that would accrue during the year. In Days per month, we take January as 31/365, etc.
This setting is available in: Register Settings > General.