The general rule is that a general partner is liable for all debts of the partnership. If you wanted to be shielded from liability, the partnership should have been set up as a partnership with a general partner and limited partners, whose only risk would be the loss of their investment. Since you are a general partner the IRS takes the position that you are involved in the business and are liable for these taxes. Even if you have an agreement with the other partners that they will not hold you liable for debts, that agreement will not be valid against the IRS since they did not agree to it.