The National Tax Lien Association (NTLA) is the trade group that represents investors, lenders, service providers, and government officials as it relates to tax lien sales. It is also the sponsoring organization of the only certification program for tax lien investors, offering a Certified Tax Lien Professional (CTLP) credential. While you don’t need certification to invest in tax liens, a CTLP certification provides you with a reliable assessment of your knowledge and skills. CTLPs are also hired by lenders, real estate organizations, and government organizations associated with the practice of tax lien sales.