Do you have a source for that 'understanding'?
It certainly goes against the experience of many people (us included) that tax from a B&B business is taxable under a micro regime - as long as it comes under the statutory turnover limit - and thus is specifically excluded from TVA.
The 23% figure mentioned in the original question includes tax (at 1.7%) as well as cotisations at 21.3%, which applies to a service industry (i.e. 'prestations de service') under the BIC regime. My understanding is that several people have claimed the lower rate for gites and B&B, under 'ventes de marchandises (BIC)', which is 12% (13% with tax included).
Note that these rates apply to turnover, not profit, so no other costs can be offset. If you have a large number of properties that you are renting out then you may well do better to go for a 'réel' regime where you can offset all your allowable costs and expenses and benefit from charging and recovering TVA,
You can opt for payment of tax with your monthy or quarterly declaration under the autoentrepreneur/micro social regime as above. However, if your income is low so you are not actually liable to pay income tax in France it is pointless opting to pay it; and if your income is above a certain level you cannot pay this way, you have to add the income to your normal tax return.
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