6 year rule on revising previously submitted SA returns

Hello, I ned help on getting approval to accept a revised return for 18/19. My accountant made anerror and sent in my earngings as dividends when they were PAYE. I used the following wording but HMRC has applied the 4 year limit and I want to make a case for themto accept using the 6 year limit. Any advice apprecaited. LETTER I am making a claim for overpayment relief for the tax year 2018/19. I originally entered my income from my limited company as dividends and paid tax on this basis. This income has since been classed as PAYE as a result of an HMRC enquiry. The reason for the delay in correcting the return is the enquiry has taken longer than expected and was further delayed due to COVID-19.

there is allowance under this... https://www.gov.uk/hmrc-internal-manuals/compliance-handbook/ch53500

Hi,
 

2018/19 is now out of date as the cut off  this was 06/04/23. A taxpayer cannot appeal HMRC’s refusal to accept a late claim, see SACM10030. The only challenge available to the taxpayer is Judicial Review, see ARTG12000. The links for these are included at : Self Assessment Claims Manual   . Thank you .

CH53400 allows for 6 years where the return was "careless" I've simply used the wrong wording on the first letter I think.