By my rough estimate, about 9%. Or about $650 on that $8,000 Datejust! If made in Le Chinit like Audemars Piguet, it would only cost about $7,300. (IE: $7,300 + 9% = $7950.) On a $3,900 Tudor Black Bay, the Geneva premium would come to about $325. So, not an insignificant amount.
In doing a little research, it seems that Swiss companies are taxed according to what region they are located in. Geneva (Patek Phillipe, Vacheron Constantin, Piaget) is the highest at about 24% or about 70% higher that of say, Vallee de Joux (Audemars Piguet, Brequet, Blancpain) at 14%. La Chaux-De-Fonds (Cartier, Girard Perregaux, Tag Heuer), LeLocle (Tisssot, Mont Blanc) or Fleurier (Movements), are all about 15%. Complicating this, is that for watchmakers that are part of a group, the tax rate seems to ultimately get rolled into the holding companies' HQ location. Now, some may argue that the tax is based on the watches' wholesale price. However, that cost gets doubled as part of the customary retail mark up.
Wholesale price: $3200
Geneva price with tax: $3200 + 24.2% ($775) = $3975. (Retail = $7950)
Le Chinit price with tax = $3200 + 14% ($450) = $3650. (Retail = $7300)
Incidentally, the Geneva corporate tax rate is about the same as the US tax rate @ 27%. The lower taxed Swiss areas are closer to Hong Kong's @ 16.5%
In doing a little research, it seems that Swiss companies are taxed according to what region they are located in. Geneva (Patek Phillipe, Vacheron Constantin, Piaget) is the highest at about 24% or about 70% higher that of say, Vallee de Joux (Audemars Piguet, Brequet, Blancpain) at 14%. La Chaux-De-Fonds (Cartier, Girard Perregaux, Tag Heuer), LeLocle (Tisssot, Mont Blanc) or Fleurier (Movements), are all about 15%. Complicating this, is that for watchmakers that are part of a group, the tax rate seems to ultimately get rolled into the holding companies' HQ location. Now, some may argue that the tax is based on the watches' wholesale price. However, that cost gets doubled as part of the customary retail mark up.
Wholesale price: $3200
Geneva price with tax: $3200 + 24.2% ($775) = $3975. (Retail = $7950)
Le Chinit price with tax = $3200 + 14% ($450) = $3650. (Retail = $7300)
Incidentally, the Geneva corporate tax rate is about the same as the US tax rate @ 27%. The lower taxed Swiss areas are closer to Hong Kong's @ 16.5%