Your computation and SA103 boxes

Two tabs under Tax, then Income Tax do the tax arithmetic: Computation shows the working, and SA103 boxes lays it out as the sheet you transcribe.

The Computation tab

The computation starts from your books and works down to the profit you are taxed on:

• Your books for the whole year - the trading profit from your accounts.
• Cash basis adjustment - present only if you are on the cash basis. See The cash basis and the accruals basis.
• Less capital allowance - the allowances claimed on your capital assets.
• Adjustments and allowances, net - everything on the Adjustments tab, netted off.

The result is your taxable trading profit for the tax year.

An Income Tax estimate sits beside it. That estimate assumes this business is your only income - if it is not, the card points you at the real figure on Your tax breakdown.

The SA103 boxes tab

Kontala files nothing, so somebody keys these figures elsewhere. This tab is the sheet they copy from.

Each row carries:

• The box number - what an accountant navigates a paper return by.
• The field name, in brackets - what their software imports.
• The figure in whole pounds, and the exact figure beside it.

Both identifiers are shown because Kontala does not know which route you are using.

Whole pounds

HMRC allows figures to be rounded to whole pounds on the self-employment pages, so that is the column most people transcribe. The exact figures are shown beside them so nothing is hidden.

The check at the foot

The line at the bottom adds the boxes up against the figure the Computation tab reached.

If that check ever breaks, one of the two is wrong and nothing else on the screen will tell you which. Do not file from either until it agrees.

Provisional figures

If your accounting year end is not 5 April, a tax year can draw on more than one set of accounts. Until the later accounts are made up, the screen marks the figures provisional, names the accounts still needed, and blocks the year from being closed.

See Your accounting date and the tax year.

Related

• Adjustments and allowances
• Close a tax year
• Capital assets