Who Self Assessment is for

A limited company pays Corporation Tax on its own profits. Every other kind of business - a sole trader, a partnership, a landlord - is not a separate taxpayer, so its profits are taxed on the people behind it through Self Assessment.

Kontala follows that split. Your company type, set under Settings, then Company Details, decides which screens you see:

• Limited company - you get End of Year with statutory accounts and a CT600.
• Sole trader, partnership or landlord - you get Income Tax under the Tax menu, with the figures for your Self Assessment return.

A business gets one or the other, never both and never neither.

What Kontala does

• Works out your trading profit for each tax year from your books.
• Restates it on the basis you use for tax - the cash basis or the traditional accruals basis.
• Applies the adjustments and allowances that turn accounting profit into taxable profit.
• Lays the result out as the SA103 boxes you copy onto the self-employment pages.
• Shows your own SA100 position: employment income, the main return boxes, what you owe and when.

What Kontala does not do

Kontala does not submit Self Assessment to HMRC. Unlike VAT, which files under Making Tax Digital, and payroll, which files RTI, there is no Self Assessment filing connection. You or your accountant enter the figures in HMRC's own service or in filing software.

The tax year

Self Assessment runs on the tax year: 6 April to 5 April. Kontala names a tax year by the year it starts in, so 2026/27 means 6 April 2026 to 5 April 2027, and the screen spells the dates out beside the label.

That is not the same as your accounting year. If your accounts are made up to a date other than 5 April, Kontala works out each tax year's share - see Your accounting date and the tax year.

Before the screens work

Kontala needs your trading start date, under Settings, then Accounting Dates. Without it there are no tax years to show, and the screen says so.

Related

• Self Assessment settings
• The cash basis and the accruals basis
• Company details