Solana Memecoin Tax in the UK: Pump.fun, Bonk & Fast Trades (2025/26)

Solana memecoin trading has its own tax shape. The trades are tiny, fast, and frequent — a typical pump.fun degen sees hundreds of disposals across a single session. HMRC doesn't care that the position lived for 90 seconds; every swap is a disposal of one CGT asset for another, and the maths has to be done.

Every swap is a disposal

When you trade SOL into a memecoin on Jupiter, Raydium, or directly through pump.fun's bonding curve, HMRC treats it as a disposal of SOL and an acquisition of the memecoin. The GBP-equivalent value at the moment of the swap is both your proceeds (on the SOL side) and your cost basis (on the memecoin side). When you exit the memecoin back into SOL, USDC, or another token, that's a second disposal.

A 100-trade session is 100 disposals — and the same 100 transactions become 100 acquisitions for the next position. The aggregate gain or loss is the sum across all of them. For an active wallet you cannot do this by hand; you need a tool that ingests the on-chain history and computes per-disposal gain in GBP.

Section 104 pooling and the 100-trade problem

HMRC's share-pooling rules mean you maintain a running average cost basis for each token. The first time you buy WIF the cost basis is whatever you paid. The second buy averages in. When you sell, your gain is proceeds minus the pool's average cost — not minus the most recent buy.

For memecoins this is counterintuitive because traders think in terms of individual entries and exits. The pool doesn't care which "buy" the sale relates to; it computes the average.

The same-day rule overrides pooling: if you buy and sell the same token on the same UTC day, those transactions are matched first at the same-day average. For pump.fun degens this is the rule that matters most — almost all positions open and close intraday.

Negligible-value claims for rugs

When a memecoin rugs to zero you can claim a negligible-value loss under TCGA s.24 even though you never sold. The token is "of negligible value" — effectively worthless — and the loss crystallises in the year you make the claim. You need the original cost basis, evidence the token is worth ~£0 (illiquid pool, no DEX listing, dead Telegram), and you file the claim on your Self Assessment.

The catch: the loss is only allowable if the asset was held as a capital investment, not as stock-in-trade of a business. A daily-volume memecoin scalper might cross into "trader" territory under the badges-of-trade test, in which case the rug isn't a capital loss — it's a write-off against trading income on SA103.

Failed transactions, failed swaps, and bot-trapped buys

Solana transactions can fail mid-execution — slippage too tight, MEV bot frontran you, liquidity vanished between block and inclusion. A failed buy is not a disposal: you still hold the SOL. A successful buy that immediately sells to a sniper bot at -90% is two disposals, one acquisition. The 90% loss is real and allowable, just like any other capital loss.

CryptoLens's Solana scanner distinguishes failed from successful transactions and only counts confirmed mints as acquisitions.

SOL price at the trade timestamp

The cost basis for each memecoin acquisition is the GBP value of the SOL you spent — at the timestamp of the swap, not the daily close. For a wallet that does 50 trades in an hour around a memecoin's launch candle, the difference between using hourly prices and timestamp-resolution prices can be 5-10% of the entire P&L.

CryptoLens pulls SOL price at each block timestamp from CoinGecko (with DefiLlama fallback) so the cost basis is accurate to the minute.

What to file

Solana memecoin gains go on SA108 alongside the rest of your crypto capital gains — there's no separate schedule for fast trades or for Solana specifically. The annual allowance is £3,000 for 2025/26. Total gains above that are taxed at 18% (basic-rate) or 24% (higher-rate). Losses carry forward indefinitely once registered.

Bring CryptoLens's annual report into your filing — it gives you the per-disposal breakdown HMRC expects if they query the return.