Does the R&D credit expire?

No, it is permanent (effective December 18, 2015).

The R&D tax credit has a history of continual renewals. Since it was created in 1981, it’s mostly been a temporary credit. The credit would expire periodically and remain expired for up to a year, then Congress would either extend the benefit retroactively and/or sometimes forward for up to a year.

The Protecting Americans from Tax Hikes Act of 2015 extended the R&D tax credit, retroactively to January 1, 2015, and the law made the credit permanent going forward. Now businesses and their CPAs can take this incentive into account in their long-range budgeting and forecasts. R&D Tax Credits are a dollar-for-dollar offset against past, present, and future tax liabilities. Plus, unused credits can be carried forward for up to 20 years.