1 A retired Regular officer who also is employed by the federal government and is subject to the dual compensation statutes may have that reduction reduced because of the waiver of retired pay to receive VA benefits.
If they don't, then 4 thick is usually standard for a patio slab, how large or small it is doesn't really matter. The most important part is the sub-base. Make sure you have a good gravel base. I would recommend at least 12 inches of compacted gravel. I like gravel where the aggregate (rocks) are no larger than 1.
A standard paver patio rests on a thick base of compacted gravel. This patio cover-up will save you the cost of that gravel. More important, it eliminates the backbreaking drudgery of breaking up concrete, digging up soil, hauling it all away and hauling in gravel.