The 180-Day Rule for Section 32 Solar Depreciation
A single compliance date decides whether your business claims 40% or 20% depreciation in Year 1. Here's the plain-English version.
Short answer: Under Section 32 of the Income Tax Act, businesses can claim 40% accelerated depreciation on solar assets in Year 1, on a written-down-value basis. But if the asset is put into use for fewer than 180 days in that financial year, the claim is halved to 20%. In practice, that means a commercial solar system needs to be commissioned and operational before roughly 1 October to get the full first-year benefit for that financial year. Miss that window, and the missing 20% isn't lost forever, it shifts into Year 2's normal-rate claim, but your Year 1 cash tax saving is roughly half what it could have been.
Why this date matters more than people expect
Our tax shield calculator runs the numbers for you, but the underlying rule is worth understanding on its own, because it directly affects when you should plan your installation, not just how you account for it afterward. Section 32 allows commercial solar installations (on a CAPEX, not lease-to-own, basis) to be depreciated at 40% per year on the reducing written-down-value balance, a meaningfully faster write-off than most fixed assets get. That 40% rate, however, is only available in full if the asset has actually been in use for at least 180 days within the financial year it was commissioned in.
What "under 180 days" actually costs you
If your system goes live after that roughly-October cutoff, meaning it's been operational for under 180 days by 31 March, the depreciation rate for that first year drops to half the normal rate, 20% instead of 40%. On a ₹50 lakh system, that's the difference between a ₹20 lakh Year 1 deduction and a ₹10 lakh one, which at typical corporate tax rates translates to a real difference in cash saved in that financial year specifically. The remaining depreciation isn't lost, the asset's written-down value carries forward and continues depreciating at the full 40% from Year 2 onward, but the timing of your tax benefit shifts later.
What this means for planning your installation
If claiming the full Year 1 benefit for a specific financial year matters to your business's tax planning, that's a scheduling conversation to have early, not something to discover after the fact. Site assessment, subsidy/vendor paperwork where applicable, and installation all take time, so if you're targeting commissioning before the 180-day cutoff for a given financial year, starting that process with real lead time matters more than it does for a residential system.
This is a standard income-tax provision, not specific to Uttar Pradesh, and some concessional corporate tax regimes restrict certain depreciation benefits, so confirm applicability with your CA before finalizing your tax planning around it.
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