Hi cbarrett98,
You almost certainly do not need to enter £299 in this box - this tax amount being refunded to you gradually through the year was to ensure that, by the end of the tax year, you had paid the correct amount of tax.
The 'tax refunded or set-off' box is to report lump sum refunds of tax received through PAYE after that tax year has finished.
To confirm that you do not need to declare the £299, though we would need to review your record.
Please contact us by webchat or phone here:
Self Assessment: general enquiries
Thank you.