On the Polymesh Staking Dashboard, the list of staking rewards shows one month of staking history, however, you can download it to a file from the Subscan block explorer. This file then can be uploaded to a tax software.
To do this, follow the instructions below:
1. Open the Polymesh Subscan Explorer
2. Copy the key from your wallet (starts with2) you are staking with, then do a search in Subscan:
The screenshot is on testnet where addresses start with 5. On mainnet, addresses begin with 2.
3. Click on the Rewards&Slash tab, then click on on [here] to view more relevant data:
4. Click on "View all" on right hand side:
5. Scroll down to the bottom of the page and click on the button "Download all data". It will download a CSV file with your staking history.
Alternatively, you can replace the following URL with the Polymesh key you are staking with, which should direct you to a similar page with a "Download all data" button at the bottom:
If you run into any issues, please open a support ticket on the Polymesh Community Portal.