Home Mortgage Interest Deduction: Perspective from Taxation on Savings

近年高漲的房價成為民怨之首，不動產稅制的檢討聲浪又浮上檯面，紛紛將矛頭指向短期投資炒作的交易。「打房」的稅制改革隨著輿論壓力紛起，卻仍老調重彈的圍繞著稅基評價過低、持有稅負過輕等議題，並無通盤檢討不動產稅制之缺漏，欠缺基礎改革的決心。高舉「居住正義」的旌旗，「自用住宅」總成為稅法的例外、改革者的禁地，鮮少有人對於其租稅優惠提出質疑、檢討。 現行稅制下自住不動產稅負較其它資產輕，其中以購屋借款利息扣除及資本利得輕稅之優惠最為明顯。本文利用跨期消費模型分析發現，於此租稅優惠下，個人會改以自住不動產儲蓄，扭曲個人於儲蓄量以及儲蓄管道之選擇，其給予借款利息扣除之優惠，更可能扭曲個人購置自住不動產融資管道之選擇。透過相關資料發現，近年不動產相關債務及自住不動產租稅優惠之使用成長明顯，且其租稅優惠之分配不均，惡化所得稅之累進性，降低其量能課稅之功能。過去文獻亦指出自住不動產購屋借款利息扣除之理論基礎薄弱，甚至不存在，於效率面及公平面皆帶來負面影響，應予以廢除。Negative public opinions on the boom of housing market pressure the government to come up with measures to tame the high-rising housing price, among different policies, the taxation of real estate is the focus of the debate. Nonetheless, most tax reformers aim at speculative tradings and the holding of high-priced real estates, few rethink the tax preferences on owner-occupied housing. Through an extended two-period life-cycle consumption model with housing savings, we show that tax preferences on owner-occupied housing distort decisions on which to save. Tax preferences provide incentives for individuals to save more through owner-occupied housing due to the home mortgage interest deduction in personal income taxation. Moreover, the tax-free imputed rents add on the tax preferences of owner-occupied housing. Recent financial data show rising real-estate-related debts and tax returns data show increasing income tax expenditures on owner-occupied housing. Both evidences are consistent with the conclusion drawn from the theoretical model. Overall, the special tax preferences on owner-occupied housing have negative impacts both on efficiency and equity grounds. The so-called “rationale” of providing preferential tax treatment to owner-occupied housing cannot be justified. The issue at hand is how to reform the tax system in order to remove tax preferences on owner-occupied housing, the sooner the better