The Inventory Method you choose decides how Summ (formerly Crypto Tax Calculator) tracks and calculates the cost of your transactions at the time of disposal. This affects how your capital gains or losses are calculated.

The inventory methods available to you depend on your tax jurisdiction. Some countries have specific methods that reflect their local reporting rules, and in those countries some of the general methods above may not be selectable.

For more detail on the country-specific methods:

Examples detailing the difference between the First in First Out, Last in First Out, Highest in First Out, Optimized HIFO and Average Cost inventory methods are shown below:

In the above example we sell our first purchase of BTC (purchased on 1st Jan) with a cost basis of $3,000, leading to a gain of $1,500.

In the above example we sell our last purchase of BTC (purchased on 4th Jun) with a cost basis of $2,000, leading to a gain of $2,500.

In the above example we sell our highest priced purchase of BTC (purchased on 3rd Feb) with a cost basis of $6,000, leading to a loss of $1,500.

Using the Optimized HIFO inventory method, when handling the disposal of an asset we match acquisitions of the asset prioritizing those which would lead to losses first, then gains. The exact categories are below:

Within these categories we will always prefer acquisitions with higher prices as they will lead to larger losses or smaller gains. This inventory method allows short term gains to mature into long term gains, leading to you paying less tax in the long run.

In the above example we sell a BTC that is assigned the average cost basis of the 3 previous buys. This is calculated by adding the cost basis of each BTC (12,000) and then dividing by the number of BTC held (11,000 ÷ 3) to give a cost basis of (3,666.67). When sold for 4,500, the gain on this BTC is 833.33.

PFU (Prélèvement Forfaitaire Unique) is the default method for French users and works differently from the methods above. Under PFU:

Gain = Proceeds − (Total acquisition cost × Proceeds ÷ Total portfolio value at time of sale)

Because of this, PFU results can differ significantly from the per-lot methods. For a full guide to how crypto is taxed in France — including the €305 exemption, reporting forms and the rules for professional traders — see How to calculate your crypto tax in France.

Before locking periods, ensure you've resolved the suggestions on the 'Review' page and filed the tax reports for the relevant financial years.

Navigate to Settings > Lock Periods and lock the periods. For more details about the feature, please check this guide.

Follow the steps above to change your inventory method. Locked periods will remain unchanged, ensuring they are not impacted by the update.

If you have any questions or need help, we're here for you! Feel free to reach out to us via the in-app chat in the bottom-right corner or send your inquiries to [email protected].