bpp qtn 65

qtn:

shona started business on 1 jan 2025 as a sole trader nd prepared her first set of accounts for 14 weeks to 5 april. her assesable profit for 24-25 is 13500.

we hv learnt a rule of pro rating the threshold limit right when not whole 12 months r used. so what i did is pro rated the lowe nd upper limits
lower limit 12570/52* 14= 3348 so limit being 1-3348
upper limit 50250/12*14= 13543 so limit being 3348-13534
then calcuted the nic as 3348*0%
(13500-3348)*6%

but in solution they just did (13500-12570)*6%

can u tell y they hv not pro rated as per 14 weeks?