If you've made a valid election under section 475(f), the only way to stop using mark-to-market accounting for securities is to file an automatic request for revocation under Revenue Procedure 2019-43, Section 24.02. Under that revenue procedure, the request for revocation must be filed by the original due date of the return (without regard to extensions) for the taxable year preceding the year of change (the year of change is the first taxable year the revocation is to be effective). This revocation notification statement must be attached to either that return or if applicable, to a request for extension of time to file that return. Late revocations won't generally be allowed except in unusual and compelling circumstances
