I have booked return tickets from Finnair, London to Helsinki. Is there anyway to split the ticket price for each way? I called to Finnair costumer service, but they were not so helpful. Any help?
Check the confirmation email with the ticket details; often, it contains a cryptic-looking line with those details. Here is an example for a random pick JFK to FRA:
NYC DL FRA Q75.00 652.50QKVJ00B2 DL X/AMS Q7.45 DL NYC 210.50UKVY00B2 NUC 945.45 END ROE 1.00 XT 5.89YC 7.00XY 3.96XA 37.20US 5.60AY 10.50DE 46.00OY 29.50RA 7.20CJ 7.10RN 350.00YR 4.50XF JFK4.50
If you spent a bit of thought over the abbreviations (and some google time), you can identify each leg and each tax and fee, and through that calculate the piece you care about.
Here is the respective string for a Finnair LHR-HEL (London Heathrow to Helsinki), in January 2020:
LON AY HEL 22.55ZLI2GB AY LON 22.55ZLI2GB NUC 45.10 END ROE 0.775934 XT 15.45GB 20.69UB 4.88DQ 8.88FI 1.00XU 35.66YR
Google's itasoftware explains it as:
So the first two numbers (22.55) are 20.79 Euro (in USD - I accidentially called it up in USD); 45.10 is the sum of the two; and the rest matches 1:1 - 15.45GB is "United Kingdom Air Passenger Duty APD, etc.
If you don't have that string, this obviously won't work. You could try to find a future flight with the same price you paid, and analyze that one accordingly, if they accept that - or simply divide the total by 2.