Personal income tax (PIT) piggybacking is a local surcharge levied by Subnational government (SNGs) on top of the taxable personal income or on the personal income tax liability already being levied by the central government. In contrast to tax sharing arrangements, piggybacking provides more SNG autonomy since the SNG is granted the power to set and levy the piggybacking rate, typically within certain bounds established by the central government, thereby strengthening the accountability between SNGs and their residents. Different versions of PIT piggybacking have been implemented largely in high-income countries, including Denmark, Norway, US, Canada, Spain, and Portugal. Croatia, a middle-income country, has adopted a PIT piggybacking system. While PIT piggybacking is an important source of SNG revenue in these countries, if Indonesia were to adopt a PIT piggyback, it would be one of the first few major middle-income countries to do so.