Validation at one of the 9 road border crossing points:
5 border crossing points equipped with PABLO kiosks:
Saint-Louis (west of Basel; motorway; site B10 (tourist traffic): Monday to Friday, 9am to 8pm; Saturday, 12 noon to 8pm and Site B8 (commercial traffic): Monday to Friday, 5am to 9am and 8pm to 10pm; Saturday, 5am to 1pm)
Traffic signals are in operation between B10 and B8.
Saint-Julien-en-Genevois (south of Geneva; near Bardonnex; every day, 24 hours a day).
Vallard-Thonex (east of Geneva; motorway; near Annemasse et Etrembières; customs presence every day, 6am to 8pm).
La Ferrière-sous-Jougne (south of Pontarlier ; north-west of Lausanne ; near Vallorbe ; customs presence Monday to Friday, 6am to 8pm; Saturday, 10am to 8pm; Sunday, 10am to 1pm).
Ferney-Voltaire (near Geneva-Cointrin airport; west of Geneva; customs presence every day, 6am to 8pm).
4 border crossing points without PABLO kiosks (validation by customs officer via electronic gun or manual entry of barcode digits):
Morteau / Col France / Col des Roches (Morteau sector; customs presence Monday to Friday, 6am to 8pm; Saturday, 10am to 6pm).
Delle (east of Montbéliard; secteur of Territoire de Belfort; customs presence Monday to Sunday, 6am to 8pm).
La Cure (north of Geneva; sector of Jura / Les Rousses; customs presence Monday to Friday, 9am to 12 noon and 1pm to 4.30pm; Saturday, 11am to 5pm).
St-Gingolph (customs presence Monday to Friday, 7am to 6pm)
Note: at border crossing points equipped with PABLO terminals, some terminals may be deactivated or inaccessible outside operating hours.
By train (including TGV Lyria)
General rule: validation during customs control carried out by French customs officers in the train (however this control is not systematic, and customs officers are sometimes dressed in civilian clothes)
If arriving at Geneva-Cornavin station: validation at the French customs desk at the train station.
Absence of French customs officers at road border crossing or during train travel
Thanks to an agreement between Swiss and French authorities, there was a procedure allowing, in case of the absence of French customs officers, to use the "declaration boxes" belonging to Swiss customs to deposit your forms. These were then transmitted by Swiss customs to French customs for regularization. French customs validated these forms and the tax refund could then be processed.
Unfortunately, from July 1st, 2023, this arrangement comes to an end. Swiss customs officers will no longer transmit the forms to French customs for VAT refunds. Eligible travelers for tax refunds who have made purchases in France, Belgium or Spain and who wish to be refunded for this tax must necessarily go through an open French border post (see list above) to have their forms validated, either electronically or with a customs stamp.
More information can be found here