How it works

HMRC calculates your end-of-year tax estimate based on the information you provide. This includes:

• Income from all your sources
• Additional personal income
• Relevant tax adjustments and allowances

Sage doesn’t calculate your tax. Instead, HMRC processes your submitted information to create the estimate.

For detailed guidance, visit gov.uk/estimate-income-tax.

Accuracy of your estimate

The accuracy of your tax estimate depends on the completeness and accuracy of the data you submit to HMRC.

Your estimate may be less accurate if you:

• Haven’t included all your income and expenditure data
• Haven’t provided complete tax adjustments or allowance information
• Omit individual income details

When you pay your tax

Your tax estimate doesn't require immediate payment. Actual tax becomes due only after you complete and submit your final declaration at the end of the tax year.

Remember, this estimate is a helpful planning tool and does not represent your final tax bill.