Unsure if the automated Tax Calculation is correct

I am both employed and self employed. Completing the self assessment tax return 2021/2022 the total requested is almost triple than my basic math. My self employment has not been profitable in the last 2 years due to COVID. I received the SEISS grants and took a temporary job which resulted in a permanent contract. When completing the self assessment I have added PAYE amounts as follows: This employment pay £31482.98 Tax paid from employment £3780.60 Income from self employment x Expenses x SEISS grants x Total taxable profits: £1403.00 According to my math the calculation should be: PAYE + Profits = 32885.98 (under £50k BASIC income rate) MINUS Tax free allowance £12570.00 = taxable income of £20315.98 x 20% = £4063.19 total tax MINUS £3780.60 ( tax paid at source from employment ) = £282.59 The tax summary shows Total amount due for 2021-22 : £995.40 Please note no adjustments or losses carried forward. I tend to go with the simple cash accounting. How is this correct? Any guidance is welcomed.

Hi,
 

Without having access to your record to see if there is an underpayment or some pther debt in your code, we cannot confirm. As personal details should not be given on the forum, you will need to telephone 0300 200 3300. Thank you.

Thank you for your reply. I figured it out in the end by clicking on view your calculation. The breakdown shows the difference is for my student loan.