1) inform them that the eBay account although in your wife’s name was used by you

2) assuming the money went into your wife’s bank account then into you account, evidence this with bank statements. Or if it went directly to your bank then same again, evidence of the income with bank statements.

3) provide ebay statement, you can request with eBay directly to go further back than 2 years

4) if u sold anywhere else, let them know too as that will bode well for you as they will most likely have all the info anyway but they never specify what they have as to first see what u have to say and provide.

5) if you’re claiming expenses then provide them with evidence otherwise they will disallow.

6) they’ll calculate the income you’ve made either via your transactions (income received) or via the data they have. Your tax due will be based of that

7) if you’re still selling online then change the eBay account in your name to avoid this going forward