To include your foreign employment income on your tax return, per HMRC guidance, you should:
1. Include employment income on SA102 with no tax entered
2. Include both employment income and tax paid on Foreign income SA106 pages.
3. Manually calculate foreign tax credit relief (FTCR) using helpsheet 263
Firstly, you must add an Employment page SA102:
Include the Employment income only from the foreign country, with no tax paid figure entered in BOX 2. This brings the income into the calculation.
Next, you must add in Foreign Income SA106 pages:
Finally, you must use HS263 to calculate the maximum allowable tax credit against the foreign income per the double taxation treaty and enter this on the Foreign Income SA106 pages > EDIT > BOX 2 - FTCR
This should successfully include the income in your tax calculation and allow for the tax credit to be deducted too.
Please note, you can leave BOX 2 on Foreign income SA106 pages blank and submit your tax return if you wish for HMRC to calculate the FTCR on your behalf.
Guidance notes to help you: