https://www.gov.za/services/services-residents/world-work/tax/register-provisional-tax-payer
Register as provisional tax payer | South African Government
If you earn income other than a salary or an allowance, you must register as a provisional taxpayer. You must then pay tax in advance in at least two amounts...
south african governmentregister asprovisional taxpayer
https://www.belastingdienst.nl/wps/wcm/connect/en/individuals/content/why-do-i-receive-a-provisional-assessment
Why do I receive a provisional assessment as a non-resident taxpayer? | Tax Administration
You will receive a provisional assessment if we expect you to pay tax over the coming year. This is to avoid having to pay a large amount at once.
do itax administrationreceiveprovisionalassessment