Margin trading and liquidations in Spain: tax guide
Margin trading gains/losses: Capital gains/losses same as spot trading (leverage doesn't change tax type)
Margin loan interest: Deductible expense
Funding rates: Paid (negative) = deductible; Received (positive) = capital income
Liquidations: Forced close = real capital loss (the full margin lost). MUST be declared to offset future gains.
kointax correctly handles all margin trading events, interest deductions, and liquidations.