authority: 5 U.S.C. 301 and 552; 26 U.S.C. 4181,4182,5123,5203,5207,5275,5367,5415,5504,5555,5684,5741,5761,5802,6020,6021,6064,6102,6155,6159,6201,6203,6204,6301,6303,6311,6313,6314,6321,6323,6325,6326,6331,6401,6407,6416,6423,6501,6511,6513,6514,6532,6601,6602,6611,6621,6622,6651,6653,6656,6665,6671,6672,6701,6723,6801,6862,6863,6901,7011,7101,7102,7121,7122,7207,7209,7214,7304,7401,7403,7406,7423,7424,7425,7426,7429,7430,7432,7502,7503,7505,7506,7513,7601,7608,7622,7623,7653,7805