Tax on crypto transactions

Yes.

According to IRAS (e-Tax Guide)

Use of digital payment token as payment

6.1 The use/provision of digital payment tokens as payment for anything (other than for fiat currency or other digital payment tokens) is disregarded as a supply for GST purposes.

6.2 If you are paying digital payment tokens in return for goods and services, you need not account for output tax.

6.3 If you are receiving digital payment tokens in return for your supply of goods or services and you are GST-registered, you would have to account for output tax on your supply of goods or services (unless the supply is an exempt, zero-rated or out-of-scope supply).

Example 4 – Use of digital payment tokens as payment GST-registered company A uses Bitcoin to purchase software from GSTregistered company B. With effect from 1 Jan 2020, Company A will not be considered as making any supply of Bitcoins and thus, will not need to account for output tax. Company B will have to account for output tax on its supply of software.