If you were made redundant and received a redundancy payment, only the taxable elements of your settlement (such as unpaid wages or any redundancy payment over £30,000) should be included in your P45 and entered in the main employment section.
Statutory redundancy payments (and the first £30,000 of any compensatory redundancy payment) are not taxable, are not subject to National Insurance, and should not be included on your P45. These amounts should be entered separately in the redundancy section of your tax return, not as part of your employment income. This ensures the correct tax treatment is applied to each part of your settlement.
In Gosimpletax, you would show this in the Income section of the Employment Page. If you have not done so already, you can add this page by clicking the + NEW PAGE button on the left of the screen:
Then select Employment (SA102) from the list shown:
Once you have added the Employment Page, you need to click the + INCOME button:
then select 'Redundancy Payment' from the list shown and then complete the relevant boxes:
You can download a copy of the tax return at the bottom of the Report Page to check your entries.