Under Ten
When you ask a tax accountant about saving on taxes, the first question back is, "How about buying a car?"
Japan's tax code is full of concepts that don't sit right with intuition. Depreciation is one of the rare ones whose skeleton makes sense. Buy something for ¥1,000,000 that you'll use for five years, and you expense ¥200,000 a year. In practice, you get straight-line and declining-balance methods. You get rules per industry. Easy to understand, it is not. Even so, the underlying idea is straightforward.
The trouble is that the law decides "how long you'll use it." Useful life. A regular car is six years; a PC is four. With smartphones, opinions split. Treat it as a phone, or as a PC. The category you assign decides the years. A device whose battery has swollen enough to push the back panel off can still hold tax value on paper. The thing is physically dead, and you're still paying fixed asset tax on it.
To soften the pain, a few escape hatches exist. Under ¥100,000, expense the whole thing on the spot. Under ¥200,000, three-year straight-line. For small and medium businesses, anything under ¥300,000 can be expensed in one shot, up to ¥3,000,000 a year combined. I think that's still the rule. They tinker with it now and then, so I'm not certain.
Still, no tax accountant tells you to "buy a PC." What they recommend, every time, is a car. ¥3,000,000 or ¥4,000,000 moved in a single stroke. And if you buy one that's six years old or more, the useful life shrinks to twelve months. That's what the formula for used assets gives you. Effectively, you write the whole thing off in a year.
Where it quietly starts to matter is the certification of "what counts as used." A car has provenance. Who registered it, when, how many years it was driven — all traceable on paper. So the "already depreciated" treatment holds.
A PC doesn't have that. There's no document for a CPU, a stick of RAM, or a GPU certifying when it was manufactured and when it started being used. With a GPU you at least have a public release date, and if you're lucky, the original receipt. Server hardware has factory shipping records, and maintenance history attached at the manufacturer. None of that flies for tax purposes, apparently. The reasoning escapes me entirely, but a GPU pulled from an Akihabara junk shop and a used server that came off a vendor's maintenance contract both sit on the asset register next to brand-new hardware.
When you run a tiny company, the optimal move chooses itself. A machine you can buy for under ¥100,000 that'll hold up for a while. The non-engineer staff PC ends up being a used M-chip MacBook Air. New, it's ¥140,000; used, it dips below ¥100,000. I'd rather hand someone a new one. I'd just rather not depreciate it over four years. So I keep buying older Macs.
The skeleton is supposed to be straightforward. Lean on that simplicity, optimize around it, and you drift away from what you actually wanted to give people. Depreciation, after all, isn't easy to understand.