Rein has extensive experience in tax litigation, and in advising or assisting with complicated tax matters such as in the structuring of corporate and commercial transactions.  She has represented, advised, or assisted clients in a diverse range of industries such as energy, mining, manufacturing, transportation, and pharmaceuticals. 

Rein’s tax litigation experience includes those involving national and local tax assessments, tax ordinances, and claiming refunds of various internal revenue and local taxes before the Court of Tax Appeals, various Regional Trial Courts, and quasi-judicial bodies such as the Central Board of Assessment Appeals and various Local Boards of Assessment Appeals.  She also regularly advises and assists clients in negotiations with the Bureau of Internal Revenue, local government units and host communities on disputes and compromises involving taxes, and in obtaining opinions from local tax authorities.

Rein also regularly advises clients on various issues in relation to Philippine tax laws, which include the efficient structuring of investments and transactions, availment of tax incentives, tax treaty relief and estate planning.  She also regularly advises or assists clients with tax compliance requirements relating to their businesses, and in complying with audit investigations.

Rein is recognised by The Legal 500 Asia Pacific as a Next Generation Partner from 2022 to 2023, and as a Next Generation Lawyer/Rising Star from 2017 to 2021.