MONROE - The Monroe Post Office is offering tax mailing tips to those who still need to file.- Taxpayers are urged to avoid typical errors made when mailing their returns, including unsigned forms, not enough postage and depositing returns in collection boxes after the pick-up time.- Use pre-addressed labels where possible. Write clearly; take special care to ensure that handwritten envelopes are legible and include a return address.- Use first-class postage - The Internal Revenue Service recognizes the first-class letter postmark as proof that the return was mailed on time.- Affix sufficient postage. The price to mail a one-ounce first-class letter is 45 cents, 65 cents for two ounces, 90 cents for one-ounce first-class large envelopes and $1.10 for two ounces.