The past tense of dot the i's and cross the t's is dotted the i's and crossed the t's.

The third-person singular simple present indicative form of dot the i's and cross the t's is dots the i's and crosses the t's.

The present participle of dot the i's and cross the t's is dotting the i's and crossing the t's.

The past participle of dot the i's and cross the t's is dotted the i's and crossed the t's.