Planning tool

Year-end timing calendar — month-by-month planning

Reviewed by the Commercial Solar Finance editorial team (we take no installer or lender commissions). Last reviewed: 14 October 2026.

Work backwards from your accounting year-end to see what to settle and when. The allowances that apply to solar have no end date; this calendar is about which period the relief lands in.

How to use it

Find your accounting year-end, then read the table from the bottom up: the last row is the claim, the first row is the route decision.

What it is not

It is not a deadline tracker: there is no deadline for the Annual Investment Allowance or the 50% first-year allowance on solar.

Working back from your year-end

WhenWhat to settleWhy
More than a year before the year-endChoose the finance route; check AIA headroom for the periodThe route decides who claims the allowances (finance route checker)
Several months beforeSurveys, quotes and the DNO connection application where one is neededConnection offers can take months; see the DNO export limits guide
Before you signConfirm which accounting period the contract and payments fall inThe claim is for the period in which the expenditure is incurred
Installation and commissioningKeep the contract, invoices and commissioning certificateThey support the claim
After the year-endClaim in the tax return for the periodgov.uk sets the £1 million AIA limit

Because the Annual Investment Allowance and the 50% first-year allowance for special-rate assets are permanent (gov.uk), missing one period moves the claim to the next rather than losing it. The rules and sources are on the capital allowances on solar panels page and in year-end tax planning for solar panels.

Frequently asked questions

Is there a deadline to claim capital allowances on solar?
No end date applies to the Annual Investment Allowance or the 50% first-year allowance for special-rate assets. You claim for the accounting period in which the expenditure is incurred.
What if I miss my year-end?
The claim moves to the next accounting period. Check your AIA headroom for that period with your accountant.

Finance route checker

Which finance route fits your solar project?

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