Self Assessment - Pension Net submitted not gross

I have recently realised due entirely to my oversight that over the last few years I may have submitted Net figures for all or part of my self assessment pension contributions and not Gross for Employee pension contributions to my work scheme and my contributions to my personal pension. What would be the recommended best course of corrective action and for how many years could the correction apply and is it worth the effort for a high rate tax payer? I am reworking all my calculations to be sure but next action will be based on the recommendations. Thanks

Not HMRC, if your work pension scheme takes in to account the pension payments before calculating PAYE then they shouldnt be on SA at all (relief already at source at highest rate as not included in taxable pay). If payments were taken after tax calculated then its the gross amount for SA, also grossed up amount of payments to any scheme outside of employer. If a higher rate payer then yes probably worth doing as higher rate relief available...can go back 4 years, involves amending the SA's for each year, you could try a letter detailing the errors to HMRC in first instance.