Taxpayer filing an original return, based on an SFR does not reset the CSED.

There is no authority to abate an assessment based on a defaulted statutory notice of deficiency prepared from a section 6020(b) return just because a taxpayer later files a return reporting tax already assessed.

See https://www.taxnotes.com/research/federal/irs-private-rulings/legal-memorandums/service-advises-on-questions-stemming-from-collection-statute-expiration-date/1ffg2?highlight=ILM+200421002