The R&D payroll tax credit election has to be made on the original return, filed on time.
David Wiener describes the founder who learns about the payroll offset after filing without the election. Extensions count, amended returns don't, so the payroll door is generally closed for that year. The credit can still carry forward against income tax.
From The Tax Strategy Playbook.
Full episode: https://taxstrategyplaybook.com
No-cost analysis through CSSI: https://calendly.com/david-wiener/cs or 770-224-8504, option two
This is educational content, not tax advice for your situation. Talk to your tax professional.