Make sure you did not misunderstand what the lender is asking for. Asking for a completed 2024 tax return this early is unreasonable. If the person you are working with says that's what they need, see if you can speak to someone else, perhaps higher up in the organization, who might have a better understanding of how tax return filing works. The person you are talking to might be working from a checklist that he himself does not fully understand.
If the lender is really insisting on a completed final tax return in January, you should look for a more reasonable lender.
1099-NEC forms, W-2s, and other income reporting forms do not have to be sent out until January 31. In many cases income reporting forms for investments, such as 1099-B or 1099-DIV, do not have to be sent out until February 15. But people do get mortgages in January. There must be mortgage lenders who are more realistic about the documents that they ask for.
