Share Cost Calculator for Ireland

About this calculator

What you can do with it

Add your buy and sell trades for a single asset (up to 10 trades). The calculator works out which shares were used in each sale, what they cost you, and your gain or loss. You can then use those figures in our Capital Gains Tax calculator to estimate the tax you owe.

How share matching works in Ireland

If you bought shares in the same company more than once, you probably paid a different price each time. When you sell, you need to know which shares you sold and what they cost. Ireland has rules that decide this for you.

The main rule is FIFO (first in, first out). Your oldest shares are always sold first. For example, if you bought 100 shares in 2021 at €10 and another 100 in 2023 at €20, then sold 100 shares today, FIFO says you sold the 2021 shares. Your cost is €10 per share, not €20.

There is one important exception. If you bought shares in the same company within 28 days before selling, those recent shares are matched to the sale instead of following FIFO. This is called the 28-day matching rule. It can change your gain or loss significantly. Our guide to Capital Gains Tax explains both rules in more detail with worked examples.

What this calculator does not cover

This calculator handles the basics. There are some things you will need to do separately:

• Currency conversion. If your trades were in US dollars, sterling, or another currency, you need to convert each amount to euro before entering it here. Ireland uses the ECB rate from the date of each trade.
• Stock splits. A split changes the number of shares and the cost per share. You would need to adjust your earlier buy trades before entering them.
• Multiple assets. This calculator handles one asset at a time. If you hold shares in more than one company, you need to run it separately for each one.
• Loss deferrals. If you sell shares at a loss and buy the same shares back within 28 days, the loss may be restricted until you sell the replacement shares. This calculator does not track that.

Submyt handles all of this automatically: currency conversion using ECB rates, stock split adjustments, multiple assets across your full portfolio, loss deferrals, and Revenue-ready reporting. Your tax position updates in real time after every trade, so you always know what you owe and can budget accordingly rather than being caught off guard with an unexpected bill at the end of the year.