 # Linear depreciation for 10 years is not 10%

This is clearly an error. With linear over 10 years the rate is 10%
10% of 2335 is exactly 233,50 not 223,45.

In another topic I think we should debate some corrections & new features.

This is because 2024 is a leap year so there is one more day for the last year. So depending on how far in the year the last depreciation happens, the rate may be a little less than 10% to follow the curve.

? A leap year in 2024 normally has no effect whatsoever upon the annual rate which is 10% in this case.
Rules (for France at least) found here: https://bofip.impots.gouv.fr/bofip/4686-PGP.html

It does when the computation method is based on the actual number of days.

I could not find where the computation method is defined.

? but a year is a year. The annual amount is 10% (in this case).
For a monthly depreciation, if equal at 30days basis then 10%/12, otherwise the sum of the monthly amounts must add up to the yearly amount. That’s the accounting definition AFAIK.

Not when you have to ratio in the year.

All months do not equal to 30 days, so same behavior.

No because there a start period which is not necessary full.

From whom?

It is under ‘taux’… which is an annual rate determined by the lifetime of the asset in question.
10 years == 1/10 = 10%
I believe accountants would pull out any remaining hair if proposed rates other than
1/(1…100) that is where the denominator is an integer year between 1 and 100 years.
[note that the bigger the denominator, the more sparse it is…]

It is a certified accountant that should be consulted here as they are also fiscally competent.

I can not find it, please provide an URL that point to it.

I filled Issue 8743: Use fixed year of 365 days - Tryton issue tracker to avoid confusion with leap years which reduce the rate by increasing the period.

AFAIK In Germany the accounting (and the banking) year has 360 days.

Wikipedia entry: https://en.wikipedia.org/wiki/Day_count_convention

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Interesting document link found here: http://www.dwheeler.com/yearfrac/excel-ooxml-yearfrac.pdf
Though I’m curious if it is up to date given being created over ten years ago.
https://dwheeler.com/yearfrac/

In the german income tax law the depreciation must be always computed by year. If the purchase date is within the first year, then the value for the first year is computed by month beginning with the month of the purchase. As either the year or the month is used for computing the depreciation the problem that is discussed here could not happen.

 http://www.gesetze-im-internet.de/estg/__7.html (§7 (1) Sentences 2 and 4)

Note: This is tax law. There is also commercial law which may allow a different way of computing the depreciation for the first year. But most SME will choose to use the accounting principles of the tax law, so we should stick with that.

There will be no significant difference to depreciate using a ratio for the first year from the purchase date using 365 or 360 days.
And if you have to compute by month, you must set the start date at the beginning of the month instead of the exact purchase date (and idem for the end date).

In France, only with digressif method is the date forced to the beginning of the month, otherwise it is by obligation the actual date the asset effectively enters into service.