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Reference Data

ShareCalc uses reference data to identify assets, fill in information about them, and supply market exchange rates. Reference data assists the calculation; it is not evidence that an unmatched asset has the opposite classification. For example, a fund that is not matched in the HMRC data is not necessarily a non-reporting fund.

Reference sources are matched only using exact identifiers such as an ISIN or SEDOL. Names and symbols are not used because they are not reliably unique. A source can fill fields that are blank. Information you have already saved is not silently replaced: a disagreement affecting the tax calculation is shown in Tax Issues so that you can review it.

HMRC Reporting Funds

ShareCalc uses the HMRC list of approved offshore reporting funds to identify offshore funds and propose their reporting status. Matching uses a checksum-valid ISIN for the exact share class.

HMRC publishes the dates on which reporting status commenced and, where applicable, ceased. ShareCalc retains these ranges and interprets them as follows:

  • A continuous history that remains current supports a Reporting proposal.
  • A history that has ceased or contains a genuine gap cannot support Reporting as a single status for the asset, so ShareCalc conservatively proposes Non-Reporting.
  • If HMRC's ranges contradict each other, ShareCalc identifies the asset as an Offshore Fund but does not propose a reporting status. The conflict is shown in Tax Issues.

ShareCalc currently supports an offshore fund as Reporting only when it had reporting status throughout your period of ownership. See Scope and Limitations.

Coverage and Identifiers

As of 2026/08/25 over 18,000 of 124,140 rows in the HMRC file do not include a valid ISIN. ShareCalc cannot match against rows with a missing ISIN so these rows are effectively ignored.

Consequently, the absence of an automatic match does not mean that the fund is Non-Reporting. Check the exact share class and applicable dates in HMRC's list, then enter the asset type and reporting status manually if necessary.

UK Gilts

ShareCalc uses the UK Debt Management Office's published gilt data. A gilt can be matched by ISIN or by SEDOL. The reference data can supply its official name, identifiers, redemption date, and coupon payment dates.

Coupon dates you enter take precedence and will not be mixed with DMO data. If your dates differ from the DMO's dates, ShareCalc uses yours and reports the disagreement in Tax Issues. A conflicting asset type or redemption date is handled in the same way.

The gilt database is included with the application. It contains historical as well as currently issued gilts so earlier holdings can still be identified.

Exchange Rates

ShareCalc can use either European Central Bank reference rates or HMRC monthly exchange rates to value supported currencies in sterling. You can choose which reference source to use in the Valuations page and it will apply for the tax calculations in the current open file. Using the ECB rates is the default for new files.

ECB generally publishes rates on business days, so a weekend or other date without a rate uses the most recent earlier rate. HMRC publishes one rate ahead of time that applies throughout each calendar month. There is no fallback for a month without an HMRC rate.

  • HMRC monthly exchange rates are available from January 2015
  • ECB exchange rates start from 1999, but coverage can vary for each currency

Not every currency is available in the reference exchange rates. If a currency code is missing, unrecognised, or unsupported by the selected source, add your own valuation for each date on which it is required. User valuations take precedence over automatic rates. See Valuations for the full valuation hierarchy and pending rate behaviour.

Sources and Attribution

The reference sources used by ShareCalc are:

HMRC and DMO information is used under the Open Government Licence v3.0.