Can night currency count towards day currency?

Nick has two questions about currency:

If I do 3 full stop landings at night, do I have to do 3 T&G’s and/or full stop landings in the day time time to fly as PIC during the day or do my night landings take care of the day requirement?

Do I have to complete 3 FS landings in both a tailwheel aircraft and non tailwheel aircraft to be current to act as PIC at night in both types of aircraft?

To answer your first question, your three takeoffs and landings to a full stop at night will also fulfill the recent flight experience requirements for day currency. If you never flew during the day, and did a full stop landing at night weekly, you’d still be legal to carry passengers day or night. Remember, you aren’t maintaining currency to act as PIC, you’re staying current to carry others in your airplane.

As for your second question, to be current in a tailwheel airplane, you must do landings in a tailwheel airplane. There is no such limitation on tricycle gear (or bicycle gear, for that matter). It’s like the old rectangle/square rule—tricycle currency doesn’t apply to tailwheel aircraft, but tailwheel currency works for tricycle aircraft. If you want to dig through the regs, FAR § 61.57 (a)(1) and (b)(1) is the place to look. There’s a lot in there, but most of it is aimed at pilots with instrument ratings or with jobs flying jets.