When you think about accounting you have to use, basically, logic. By that what I mean is, you have to think where this Social Insurance Contributions went in your accounting books when were paid. Using your example, contributions made by the employer that are related to Payroll, like disability insurance, unemployment, etc., in some point were registered in your accounting if you have the correct setup. Example:
Wages Expense 5,000
Employer contributions (Expense) 1,000
Employee deductions (Payable) 1,000
Employers contributions (Payable) 1,000
Wages Payable 4,000
If you follow this example, then when you as employer pay the deductions and employer contributions you have to split your transaction to decrease the balance payable in both accounts (I used two in the example but many people use just one account for employee and employers contributions payable). Then, if you paid, lets say 3,000 then your payable balances would be in negative, so the difference is what the refund should be and must be allocated to the payable account.
That is if the things are easy. In practice, if this Social Insurance was an expense account then you should put this refund to the same account and the expense will decrease by this same amount. Another possibility is that you never registered this excess in your books. The correct way then should be to allocate this to the
retained earnings account because this transaction is, in fact, from prior years; this is commonly known as
prior year adjustments in accounting.
Bottom line: I don’t think that you should do the wages adjustment. This adjustment would then give you an incorrect balance and what you’re trying to do for what I see in the post is to correct the amounts that were paid in excess. What I would do is first to check if this overpayment is registered in your books. Look into the tax due or tax payable accounts and if they are up to date then you should only see the current balance. If there’s less, then that’s your overpayment (in theory).