One time basis for the whole file: what mixing UTC and local time does to FIFO and the per-year Summary (record-keeping only)

Not tax advice. All numbers, tokens and signatures below are EXAMPLE data. This guide covers record-keeping only. How any of this is treated where you live is a question for a tax professional.

Trade logs are stitched together from explorer exports, wallet screens and exchange files. Some stamp trades in UTC, others may show local time. Copy dates from both without converting, and the same night can carry two dates. Here is what that does to trade order and per-year totals, in three EXAMPLE nights recalculated in the shipped Nah Crypto Tax Tracker workbook.

Where the times come from

Solscan's export documentation shows its "Human Time" column as UTC text ending in Z, e.g. 2026-05-18T18:22:52.000Z (pro-api.solscan.io). Google documents that its EPOCHTODATE function returns UTC, "not the local time zone of your spreadsheet" (support.google.com). For every other source, check before you copy.

The workbook's Instructions say: "Year-end uses the date you enter; use UTC timestamps consistently." It never sees a time zone.

The setup

All three examples assume a trader whose local time is two hours ahead of UTC. Late-evening UTC trades are therefore already "tomorrow" locally. In each case, one row was copied in local time and the other in UTC. All prices and fees are EXAMPLE values in fiat.

Night 1: a buy and sell in the same night turn into OVERSOLD

PUMPY: a buy at 22:30 UTC and a sale at 23:15 UTC on 14 March 2025. Locally that's 00:30 and 01:15 on 15 March.

Basis	Buy dated	Sell dated	Check	Realized
All UTC	2025-03-14	2025-03-14	OK	+49.60
All local	2025-03-15	2025-03-15	OK	+49.60
Buy local, sell UTC	2025-03-15	2025-03-14	OVERSOLD	none

In the mixed version the sale is dated a day before the buy. The workbook checks each Sell only against earlier Buys (on the same date, only Buy rows above it count), finds none, flags the row OVERSOLD and calculates no cost or result for it. The PUMPY holdings line then shows 0 units but a remaining cost of 100.20.

Night 2: two buys swap places, and FIFO picks the wrong lot

BOLT: buy A (1,000 at 1.00) at 22:30 UTC on 9 May 2025, then buy B (1,000 at 2.00) at 23:00 UTC the same night. On 12 May, 1,000 BOLT are sold at 1.50.

All UTC or all local: A comes first, the sale's FIFO cost is 1,000.00, realized +500.00, and the remaining 1,000 BOLT carry a cost of 2,000.00.
A copied in local time (10 May), B in UTC (9 May): B now looks older. FIFO takes B, the cost becomes 2,000.00 and the result is −500.00. The remaining holding shows a cost of 1,000.00.

Every row still says OK. Nothing was oversold, so no flag can catch this.

Night 3: New Year's Eve with mixed sources

FLIP: a buy at 22:20 UTC and a sale at 22:50 UTC on 31 December 2025, which is just after midnight locally.

All UTC: both rows are dated 2025-12-31, and +49.80 lands in the 2025 row of the Summary.
All local: both are dated 2026-01-01, and +49.80 lands in 2026.
Buy local, sell UTC: the sale (2025-12-31) comes before the buy (2026-01-01) and is flagged OVERSOLD. The result appears in neither year. The buy's 0.10 fee is in 2026, the sale's 0.10 fee in 2025.

With all three nights in one file, the totals are 599.40 for both consistent versions; only the split between 2025 and 2026 differs (599.40 / 0 for UTC, 549.60 / 49.80 for local). The mixed file totals −500.00, with two OVERSOLD rows counted under "Rows needing attention".

Pick one basis and write it down

Choose UTC or local time once, for every row in the file, all years. Which one fits your situation is a question for a tax professional; the sheet only needs you to be consistent.
Convert before you paste. Every date you type or paste into column A follows the chosen basis, whatever the source showed.
Note it in Notes (H) on the first row, e.g. "All dates UTC; exchange file converted from local time".
Keep same-date order right. On a shared date, the Buy goes above the Sell that uses it; see same-day pump.fun flips.

Checklist

One time basis for the whole file, written in Notes (H).
Late-night trades checked twice when buy and sell came from different sources.
No OVERSOLD row that disappears once you fix a date.
For big sales spanning several lots, the lot order matches the real order; see selling in chunks.
Column M says OK, and holdings match the wallet.

Related guides

A ready-made option

The Nah Crypto Tax Tracker is an .xlsx plus a PDF guide with plain formulas and no macros: Buy/Sell rows, Tx hash in G, Notes in H, FIFO by date then row order, an OVERSOLD flag and a per-year Summary for 2024 to 2030. FIFO only; not tailored to any country's tax rules. 29 USDC one-time: Nah Crypto Tax Tracker. Not tax advice.

Not affiliated with Solscan or Google. Sources checked 21 October 2026.