Minimum depreciation value

Here, the accountant has always said: write off amounts higher than €250 excluding vAT. Personally, I would choose a 2-year depreciation here. I fear that the tax authorities will not approve anything longer than that, as it is a second-hand device anyway.

From €250 (or more, of course) and if it remains in the company for a long time (think 3 years or more), the tax authorities often expect an investment. You can still select not to write it off, but then you will have to justify that decision.

On the other hand, below 250 euros, you can and may perfectly well record it as an investment, at least if it lasts for a long time. The £250 limit is there to make things a bit simpler. Otherwise, you would also have to depreciate a £10 hole punch :)

Specifically for your piano: that seems to me to be an investment. Long-term use and higher purchase value. In terms of term, I suspect you need to think a little longer term. I'm no expert on pianos, but don't they last a very long time? You say it's a second-hand model, but even so, I would still think 5 to 10 years.