Change in dividend income

My dividend income will exceed the allowance this tax year and I expect to pay some tax on it after I declare the surplus amount to HMRC. If I dispose of shares to being the dividend below next years allowance I shall have nothing to declare. Will HMRC assume the same income as this year unless I advise them specifically?

Hi
HMRC generally works on the assumption that a source of income is ongoing, unless advised otherwise, so please call or write to HMRC when you dispose of the relevant shares and we will amend your tax code accordingly.  
Dealing with HMRC