The Palace said major work was needed to turn the house - which is in the grounds of Windsor Castle - from five separate cottages into a single home for Harry and Meghan, and their new baby Archie.
Buckingham Palace said Frogmore Cottage was in very poor shape and needed ceilings and floors replacing, extensive rewiring, and the installation of gas and water mains - but there's no mention of a yoga studio.
The renovation cost British taxpayers $4.4 million.
With taxpayer-funded spending on the royals a sensitive topic, the Palace made it clear in the Sovereign Grant Report the couple themselves paid for anything other than basic fixtures and fittings, such as furnishings and interior design.
Sources close to the couple told The Daily Mail that reports of a yoga studio or "floating floors" at Frogmore Cottage were incorrect.
"Frogmore Cottage is a Grade II-listed building, the official and only residence of the Duke and Duchess of Sussex. It is not their country residence, it is their only residence," the source explained to The Daily Mail.
"Other senior working members of the Royal Family have official residences which are paid for by the sovereign grant to enable them to carry out their royal duties.
"There's no wing for Doria, no yoga studio. It's a fairly cosy family home," the source told the publication.
