As the use of e-filing of tax returns has spread from developed to developing countries, it has been clear that this sort of reform can reduce errors and opportunities for corruption. Also, it has been widely assumed that taxpayer compliance costs would decrease with the use of e-filing, because less time is spent getting tax returns from the taxpayer to the revenue authority. This note summarizes findings from tax compliance cost surveys and offers a cautiously positive assessment of e-filing reforms in developing countries with a number of caveats. Countries should not rush to push e-filing on all taxpayers until the revenue authorities, infrastructure, and tax-payers are ready.