[PF] Is Fractional BAB a House Rule?

[Mr. Zolrane]

Since I first picked up D&D/Pathfinder my groups (both as a player and a DM) have always played with the rule that classes without full BAB get 1/2 or 3/4 respectively based on the BAB progression that their class table indicates. Yesterday, one of the players in my Pathfinder campaign was very shocked to find out that his 3.5 Warlock 5/PF Ninja 2 should have a BAB of 5, not 4. His reasoning was that if you add together the 1 in Ninja 2's table with the 3 in Warlock 5's column you get 4, not 5 and that's how every DM he's ever had in his six years of D&D/Pathfinder has played it as far as multiclassing is concerned. His wife (who is also playing and is in a similar situation as an Oracle 5/Summoner 2) corroborated his experiences (not surprising, as they've shared most of their gaming groups) and the Cerebremancer's player echoed the same. The Magus' player agreed with me, and like me, this was the first he'd heard of such a system of counting BAB.

My problem is that I can't actually find evidence for what I'm saying in black and white in the PFSRD or any of the physical books. Have I been playing with a passed-down houserule and just didn't know it, or am I just not looking in the right places?

[Douglas]

It is a variant rule from Unearthed Arcana, a 3.5 book composed almost entirely of variant and optional rules. This particular variant rule is fairly popular on these forums, and I use it in my games too. The official version of it still allows getting multiple one-time +2s to saves from multiclassing, though, and a lot of people house rule that part away.

[WildPyre]

That would indeed be a houserule. RAW the only increase you get is when the table says you go up a full point.

[Mr. Zolrane]

It is a variant rule from Unearthed Arcana, a 3.5 book composed almost entirely of variant and optional rules. This particular variant rule is fairly popular on these forums, and I use it in my games too. The official version of it still allows getting multiple one-time +2s to saves from multiclassing, though, and a lot of people house rule that part away.

That explains it. I got started in 3.5 and while I never owned a sourcebook outside of Core (other than Complete Arcane) but Unearthed Arcana is on the SRD so my first DM probably absorbed that by osmosis and it got passed down to me. Compound that with the fact that most of interacting with the larger D&D community outside of my actual group has come from these forums, where fractional BAB is taken for granted.

As for the one-time +2 to saves, multiclassing so very-nearly-always suboptimal in PF anyway (save for a monk dip for clerics or rangers) I don't really feel the need to do away with that, as most of my players who multiclass do so with my full warning that they're shooting themselves in the foot in one way or another.