Timing of tax relief - overseas income

Hi, I have two related, simple, questions about foreign income and claiming tax relief, specifically related to timings. I am resident in the UK and have recently had some income and deductible expenses (in the area of forestry) in Finland. The tax year in Finland is equal to the calendar year. My income/expenses are split as follows (approx): Jan-Mar 2023: 15k income Apr-Dec 2023: 2k income 3k deductible expenses I understand I'm liable for tax in both countries and would then be able to claim tax relief in the UK; in accordance with the dual taxation treaty. My questions are around how to account for the different tax periods. I will only pay tax on this in Finland in mid-2024, and will pay tax on net income of 14k. When I file my self-assessment in the UK for 22/23, should this include the income of 15k? or taxable income of 14k? When I file my self-assessment in the UK for 22/23, I will not yet know the exact amount of tax I will pay in Finland. Do I defer the claim for relief to a later year, or can I claim based on an estimated figure?

Is anyone able to answer these queries?

Hi
As the UK tax year runs from 6 April to 5 April you should apportion your income accordingly to coincide with these dates.  
Please see Tax on foreign income: Overview - GOV.UK (www.gov.uk).  
If foreign tax has not yet been deducted you can apply for a Certificate of Residence to present to the Finland tax authorities per the foreign income link.

Hi E,
You haven't mentioned whether you use Cash Basis Accounting or Traditional Accounting.
If you use the Cash Basis, your expenses would be allowable in the UK  tax year in which they were incurred.
If you use Traditional Accounting, expenses are recorded/allowed on the dates on which invoices are issued or bills are received.
You should declare your income and expenses in the SA return for the UK tax year in which they are accounted for.
If you don't know the exact amount of Foreign Tax Credit Relief claimable for a particular tax year, you can enter a provisional estimate and amend your return as necessary when you have paid the Finnish tax due.    
 Foreign notes Tax year 6 April 2019 to 5 April 2020 (2019–20)
Thank you.