Bulgaria

One Stop Shop - General information 

https://nra.bg/wps/portal/nra/taxes/dds-pr-sdelki-v-ES/Specialni-rejimi-za-oblagane-s-DDS-OSS

The Union One Stop Shop and the Non - Union One Stop Shop 

https://nra.bg/wps/portal/nra/taxes/dds-pr-sdelki-v-ES/Specialen-rejim-v-Suuza-i-specialen-rejim-izvun-Suuza

Import One Stop Shop (IOSS) 

https://nra.bg/wps/portal/nra/taxes/dds-pr-sdelki-v-ES/Specialen-rejim-za-obslujvane-na-edno-gishe-vnos-IOSS