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Reference

Historical FX rates: where to find them.

For retroactive valuation, tax filing, or research, you need an authoritative time series. Several free sources exist; their methodologies and coverage differ.

The four main free sources

  • European Central Bank Statistical Data Warehouse (SDW). Daily reference rates against EUR from 1999 onwards (and against ECU from 1979). Free, authoritative, machine-readable XML and CSV. Best for euro-pair time series.
  • Bank of England database. Daily rates against GBP from 1975. Quarterly averages back further. Good for sterling pairs and long historical series.
  • US Federal Reserve H.10 release. Daily noon rates for major USD pairs from 1971. The longest free series for USD pairs and the most consistent methodology.
  • IRS Yearly Average Exchange Rates. Annual averages for tax-filing purposes, US domestic.

What “historical rate” actually means

Three distinct concepts that get conflated:

  1. Snapshot. The rate at a specific moment (16:00 ECB fix on 2025-03-14). Use for tax dates with explicit-rate rules.
  2. Daily average. Average of bid and ask across the day. Most consumer apps publish this.
  3. Period average. Average across a longer period (week, month, year). IRS uses annual averages.

The differences can exceed 1% on volatile days. Always specify which type you need before sourcing.

Tax filings

  • UK (HMRC). Monthly and annual averages published by HMRC. Use the rate matching the relevant tax year (April–April).
  • US (IRS). Yearly average exchange rates table or the spot rate on the transaction date, depending on circumstance.
  • Germany (BMF). Monthly average rates published by the federal Ministry of Finance, applied per Bundessteuerblatt rules.
  • France (DGFiP). Daily ECB rates for capital-gain conversions; specific monthly rates for some PER and assurance-vie calculations.

Use the rate explicitly mandated by your tax authority. A rate from a third-party converter is not a substitute and may be rejected on filing review.

What kefinance.xyz does not do

This site does not store or serve historical rate time series. The bundled table is a single-day snapshot. For historical lookups, use the official sources listed above. We recommend the ECB Statistical Data Warehouse for euro-pair queries; the Bank of England for sterling; the Fed H.10 for USD pairs.

Long-horizon notes

Rates pre-1999 require care: many euro-area currencies were quoted against the European Currency Unit (ECU) before the euro. The ECB publishes a conversion table from ECU to EUR (the conversion is exactly 1:1 by definition on 1999-01-01, but the unit changed). Pre-1971 rates are subject to the Bretton Woods fixed-rate system and behave very differently from post-1971 floating rates.