Error 1046 is a Government Gateway / IRMark validation message. It typically appears when a mandatory box is blank, a Yes/No flag does not match the pages you included, or a calculated total does not equal the sum of its parts.
Work through the SA110 calculation, check that every selected supplementary page has data, and avoid leaving required UTR or NINO fields in an invalid format.
Assisted customers can ask us to resolve validation issues before resubmitting.
QuickTaxFiler helps you complete Self Assessment and supplementary forms. If you have questions, use chat or email support@quicktaxfiler.co.uk.
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