VA Assumption Question

[Kevin Ward]

Hello everyone.  Thanks in advance for reading and replying.

Currently buying a property through VA assumption with a second mortgage company to cover the cost above whats owed by the seller.

Underwriting for the assumption portion said they cannot consider rental income that doesn't have a documented (tax return) source.  I have a property that only has 12 months and another with a 4 months old lease.  

Does anyone know if this is a VA requirement or something the lender is using for their process?

Thanks!