I'm a member of the UK's Civil Service pension scheme nuvos which is a defined benefit scheme and I use double-entry bookkeeping software (Gnucash).
Every month this happens on my payslip:
Account Charge Income Salary Gross salary Income 1000 Net salary Bank account 600 Pension contribution ??? 200 Tax Expense > Tax 200 Employer pension contribution ??? 100
So at the end of 1 year of employment I have (200 * 12) + (100 * 12) = 3600 that I don't know where to store. Is it an expense, or an asset, or something else?
And then at the end of my first year in the scheme I received this statement:
Your pension is now worth £500. This is calculated as 2% of your pensionable gross income.
There's no straightforward way that I can work out to match up the value of these two things in a double-entry accounting system.
In defined contribution schemes that I'm a member of, this is much more straightforward because deductions from my payslip purchase "shares" which vary in value over time.