Amortised cost measurement: use effective interest rate to carry financial instruments and account for transaction cost adjustments. Entities initially recognise financial instruments at fair value adjusted for transaction costs; add transaction costs to financial assets and subtract them from financial liabilities. If on market terms, transaction proceeds equal fair value; if off market, discount contractual cash flows at market rate for similar instruments and record the difference. Measured subsequently at amortised cost using the effective interest rate method: carrying amount equals initial recognition less principal repayments plus or minus cumulative amortisation and, for assets, less impairment. Periodic accounting records unwind discounts as finance cost or income and record actual interest or principal payments.