My husband and I have a mortgage on our home, an RV and a time-share. Can we deduct the mortgage interest we paid on all three of these?

No. Mortgage interest is deductible only on your primary residence and on a second home. You can decide whether the RV or the time-share is your second home. The loans must be secured by those properties.  There are also limits on the total amount of home mortgage debt on which you can deduct the interest, which may vary depending on when the mortgage debt was incurred.  See IRS Publication 936 for detailed information on the home mortgage interest deduction.