How far back can I claim R&D tax credits?
The R&D tax credit claim has a time limit of two years from the conclusion of your accounting period.
Within this period, you must submit your R&D tax credit claim for all eligible expenditures identified during that specific timeframe.
This is because R&D tax credits fall under corporation tax relief, and the usual deadline for amending your corporation tax return is 24 months after the conclusion of your accounting period.