Singapore has no capital gains tax — long-term crypto investors may legally owe nothing.

Commonly misreported
There is no capital gains tax in Singapore at all, for crypto or anything else, so a gain on payment tokens (like Bitcoin) is only taxed if it's revenue in nature rather than capital in nature. IRAS explicitly notes that unrealized fair-value gains recognized in your accounts aren't taxable since they're not realized, and realized gains are only taxable when the disposal is assessed as trading activity under the badges-of-trade test — meaning a genuine long-term holder can legitimately owe nothing on appreciation.

IRAS looks at your intention at the time you acquired the payment tokens, applying the traditional "badges of trade" test used for any asset class — frequency of transactions, holding period, reasons for the purchase and sale, and so on. If your activity is assessed as trading rather than investing, the resulting gains (and losses) on disposal are revenue in nature and taxable/deductible; if it's investment, they're capital in nature and untaxed either way.

Commonly misreported
No. Since 1 January 2020, using digital payment tokens as payment for goods or services no longer creates a taxable supply of those tokens, so the payer doesn't need to account for GST on the token side of the transaction. The merchant receiving crypto still charges GST on the goods/services as normal if they're GST-registered — the exemption only removes the old double-taxation of the token itself.

No. The GST exemption only applies to "digital payment tokens," which by definition must be fungible — NFTs representing ownership of specific property (digital art, IP rights, etc.) are not fungible, so IRAS explicitly carves them out: transfers of such non-fungible tokens remain a taxable supply of services, just like before the 2020 digital-payment-token exemption existed.

Not automatically — it depends on why you're doing it. IRAS treats an individual miner, prima facie, as pursuing a hobby, so gains from selling mined tokens are capital in nature and untaxed and mining costs aren't deductible. But if you mine with habitual, systematic effort to profit, IRAS will treat you as carrying on a vocation, and your profits from selling the mined tokens become taxable. Companies are treated differently by default: a company mining is presumed to be running a business, so its mining profits are taxable on disposal and its mining expenses are deductible.

It depends entirely on what kind of token is issued. Proceeds from issuing payment tokens (like a new cryptocurrency) are generally taxable; proceeds from utility tokens are treated as deferred revenue, taxed only when the company delivers the promised goods or service; and proceeds from security tokens are treated like proceeds from issuing shares or debt — capital in nature and not taxable at all.